Provided are systems and methods for ground fault immune data measurement system for electric submersible pumps. A data measurement system coupled to the ESP includes a surface unit coupled to a 3-phase power cable for providing power to a 3-phase motor of the ESP and a downhole unit coupled to the motor of the ESP and located downhole in a well. The downhole unit includes sensor and is configured to generate frequency modulated carrier signals for carrying the sensor data to the surface unit. Each of the frequency modulated carrier signals carries identical sensor data and is modulated to a different frequency. The carrier signals are shunted across the motor windings of the ESP motor and onto the 3-phase power cable via a capacitive coupling. Additionally, another carrier signal carrying control data may be transmitted from the surface unit to the downhole unit.
This invention relates generally to data measurement systems used with downhole electric submersible pumps in wells and, more particularly, to data transmission and ground fault protection for such systems.
Various drilling and production systems are employed to find and extract oil, natural gas, and other resources from the earth. Oil wells of such systems may have diminished production due to conditions in an oil reservoir and use artificial lift systems to improve oil production. Some artificial lift systems may use downhole electric submersible pumps to lift oil to the surface for recovery. An electric submersible pump may receive power from the surface, such as through a cable deployed alongside production tubing. The electric submersible pump assembly may also include a data measurement system that measures various parameters. The data measurement system typically receives power from the pump power cable and transmits data though the motor windings and to the surface via the power cable. However, the data transfer rate of such systems is limited by the electrical impedance of the motor windings and the power cable. Additionally, such systems are unable to transmit data in the event of either a partial or complete ground fault.
Various embodiments for systems and methods for ground fault immune data measurement system for electric submersible pumps are provided herein. In some embodiments, a data measurement system coupled to an electric submersible pump (ESP) is provided. The system includes a surface unit coupled to a 3-phase power cable, the 3-phase power cable coupled to a 3-phase motor of the ESP and a downhole unit coupled to the motor of the ESP and located downhole in a well. The downhole unit includes a plurality of sensors and a processor coupled to the sensors and configured to receive the sensor data. The downhole unit further includes a modulator coupled to the processor and configured to generate a plurality of frequency modulated carrier signals for carrying the sensor data to the surface unit, each of the plurality of frequency modulated carrier signals carrying identical sensor data and modulated to a unique frequency. Additionally, the downhole unit is capacitively coupled to motor windings of the motor of the ESP and configured to transmit the plurality of carrier signals across the capacitive coupling and to the surface unit via the 3-phase power cable.
In yet another embodiment, data measurement system coupled to an electric submersible pump (ESP) located in a downhole region of a well is provided. The data measurement system includes a plurality of sensors configured to produce sensor data and a processor configured to encode the sensor data in a first frequency modulated carrier signal at a first frequency, a second frequency modulated carrier signal at a second frequency, and a third frequency modulated carrier signal in a third frequency. The processor is further configured to decode control data received in a fourth frequency modulated carrier signal at a fourth frequency, wherein the first frequency, second frequency, third frequency, and fourth frequency are different frequencies. The data measurement system further includes a capacitive coupling to three motor windings of a 3-phase motor of the ESP, wherein the frequency modulated carrier signals are transmitted across the capacitive coupling to a 3-phase power cable.
FIG. 12 is a schematic diagram of a two-stage switching regulator for a non-isolated downhole electronics power supply in accordance with an embodiment of the present invention.
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. The drawings may not be to scale. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but to the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.
The downhole unit includes various components, including a digital signal processor, a multiplexer and modulator, filters, and amplifiers. The carrier signals for carrying sensor data are generated at three separate frequencies, modulated with encoded data, and transmitted across each motor winding via a capacitive coupling. The surface unit includes a digital signal processor, a multiplexer and modulator, filters, and amplifiers, and receives the carrier signals from the 3-phase power cable connected to the electric submersible pump. The surface unit de-multiplexes and demodulates the carrier signals. This provides the sensor data to be input into a computer coupled to the surface unit. By comparing the measured amplitudes of the carriers, the presence and/or location of cable and/or phase faults may be detected.
FIG. 1 depicts a system 100 having a well 102 below a surface 104 in accordance with an embodiment of the present invention. The system 100 includes production tubing 106 extending downhole in the well to a subterranean resource 108, such as an oil or natural gas reservoir. As will be appreciated, at the surface, the production tubing 106 may be connected to various control and regulation devices (e.g., a “Christmas tree”), pipes, and other components for producing the oil or other resources.
An electric submersible pump (ESP) 110 may be coupled to the downhole end of the production tubing 106. The electric submersible pump may pump the oil or other resource of the subterranean resource 108 through the production tubing 106 to the production equipment at the surface 104 (e.g., as a part of an artificial lift system). The ESP 110 is connected to and receives power from a 3-phase power cable 112 that provides power to the ESP 110 for operation. The 3-phase power cable 112 is coupled to an ESP controller 114 at the surface 104. The ESP controller 114 may provide control and power to the electronic submersible pump 110 via the 3-phase power cable 112.
System 100 may include a data measurement system 116 in accordance with the embodiments described further below. The data measurement system 116 includes a downhole unit (DHU) 118 coupled to the electric submersible pump 110. For example, in some embodiments the DHU 118 may be inside the electric submersible pump assembly and may be mounted at the bottom of the motor of the pump. The DHU 118 may include data measurement sensors (S) 120. The sensors 120 may include various sensors for measuring pressure, temperature, vibration, voltage or other parameters as discussed below.
The data measurement system 116 also includes a surface unit (SU) 122 located at the surface 104 and that may be a part of the ESP controller 114. As described further below, the SU 122 may include capacitively or inductively coupled attachments that receive communication and control data from the 3-phase power cable 112 (e.g., via surface wiring) and connect to a surface communications system, such as by filters and voltage control. In some embodiments, the SU 122 is coupled to a computer 124. The computer 124 may include a desktop computer, a laptop computer, a tablet computer, a smartphone, or other computers. The computer 124 may include one or more processors, volatile memory (e.g., RAM), non-volatile memory (e.g., hard drive, a solid state drive, and so on), a display, a network interface, input and output devices, and various other components. The computer 124 may execute analysis software for displaying and manipulating sensor data, control software for controlling the components of the SU 122 and the DHU 118, and other software used in the operation of the data measurement system 116.
FIG. 2 is a simplified schematic diagram 200 illustrating the connection between the DHU 118, a motor 201 of the ESP 110, and the SU 122. As shown in FIG. 2, the DHU 118 receives serial input data 202, such as from sensors coupled to the DHU 118. The DHU also include amplifiers 204 (e.g., line drivers), a multiplexer and modulator 206, and filters 208. The sensor data carrier signals are provided via the amplifier 204A, the multiplexer and modulator 206, the second amplifier 204A, and then through the line filters 208 to the motor 201. In some embodiments, the multiplexer and modulator 206 is a modified asynchronous digital subscriber line (ADSL) type broadband multiplex and modulation system. The DHU 118 is connected to a Y point 210 (also referred to as the “star point”) of the motor 201 of the ESP 110, and the carrier signals are of sufficiently high frequency to connect across the parasitic capacitance that exists in parallel to each phase of the motor winding (as shown by capacitive connection 212). Thus, the carrier signals that transmit data to the surface shunt the motor windings via capacitive connection 212 onto the 3-phase power cable 112 and are not conducted through the motor windings themselves. Thus, the data rate encoded on the transmitted carrier signals is not limited by the inductive impedance of the motor 201 windings, enabling an increased transmission rate of sensor data.
As shown in the schematic diagram 200, the carrier signals are transmitted through the 3-phase power cable 112 to the surface and the SU 122. As described below, the transmission of the carrier signals is achieved by tuning the carrier frequencies to match the impedance of the windings of the ESP motor 201 and the 3-phase power cable 112. Additionally, ( ) the connection to the motor 201 may be a single point onto the Y-point 210 of the motor. In some embodiments, the AC voltage occurring at the Y-point may be used as a current source to power a monitor of the ESP 110.
It should be appreciated that any number of carrier signals may be transmitted in either direction, e.g., from the DHU 118 to the SU 122 or from the SU 122 to the DHU 118. Each carrier signal transmitted from the DHU 118 to the SU 122 may carry identical data, e.g., the sensor data received from the sensors of the DHU 118. In some embodiments, four carrier signals at four different frequencies are used. In such embodiments, the carrier signals may include a first carrier at 64 kHz, a second carrier at 96 kHz, a third carrier at 128 kHz, and a fourth carrier at 160 kHz. In such embodiments, the first three carrier signals may each carry identical data, e.g., sensor data, from the DHU 118 to the SU 122, and the fourth carrier signal may carry control data from the SU 122 to the SHU 118. As described below, the amplitudes of the carrier signals are used to determine the condition of the power phases and to provide a wide system bandwidth to cope with different motor and power cable characteristics.
As mentioned above, in some embodiments, an additional carrier signal may be used to carry control data from the SU 122 to the DHU 118. The control data may be used to control actuators below the motor of the ESP 110 and to set data acquisition parameters such as signal gain. In such embodiments, the control data carrier signal may have the same data rate capability as the carrier signals that transfer data from the DHU 118 to the SU 122. Thus, in some embodiments having four carrier signals, the first three carrier signals (e.g., carrier 1, carrier 2, and carrier 3) may be used to carry sensor data and the fourth carrier signal may be used to carry control data.
The SU 122 receives the carrier signals from the DHU 118 and outputs serial output data 214 to external devices, such as to the computer 124. The SU 122 may include line filters 216, amplifiers 218, and a de-multiplexer and demodulator 220. The carrier signals are received at the line filters 216 and amplified via amplifiers 218A, 218B, and 218C before being provided to the multiplexer and demodulator 220. The demodulator 220 locks on to the carrier frequencies and recovers the original signal used to modulate the carriers. The demodulated signal is then amplified via amplifier 218D and output as serial output data 214. Additionally, as described below, the amplitude of the carrier signals may be analyzed to evaluate line or phase problems.
FIG. 3 depicts a detailed schematic of the DHU 118 in accordance with an embodiment of the present invention. The DHU 118 may include sensors that transmit sensor data via a connection to the Y-point 210 of the ESP motor 201 via the components described below. As mentioned above, the DHU 118 may include various sensors 120 that provide data measurement of different parameters. The sensors 120 may include pressure sensors (e.g., quartz type, strain gauge type), temperature sensors, vibration sensors, voltage and current sensors, and a differential pressure sensor array for a flow meter. In some embodiments, the differential pressure sensor array may include four pressure transducers. In some embodiments, the sensors 120 may include: two pressure sensors, two temperature sensors, two vibration sensors, four pressure sensor for a flow meter, and four voltage and current sensors. The data measured by the sensors 120 may include pump bearing data 300, carrier amplitude data 302, flow meter data 304, and pressure, temperature, and vibration data 306.
The DHU 118 generates the carrier signals for the sensor data and may include phase protection and power supplies for sensors and actuators. In some embodiments, the sensor data is updated every second, every two seconds, every three seconds, every four seconds, or every five seconds or greater. In some embodiments, three carrier signals are generated for carrying signal data from the DHU 118 to the surface. In some embodiments, the three carrier signals are frequency modulated carriers of 64 kHz, 96 kHz, and 128 kHz separated by 32 kHz guard bands. In some embodiments, the carrier signals are modulated as direct digital data or frequency shift keying (FSK) digital tones. In such embodiments, side bands may be developed that are separated in each carrier spectrum by about 16 kHz. Moreover, in some embodiments the three carrier signals are delayed in the time domain to ensure that two carrier signals will be ahead of or delayed on an occurrence of power switching at a data transition point of the third carrier signal. Additionally, the carrier signals' frequencies are completely independent of the power line frequencies of the 3-phase power cable 112.
The DHU 118 includes a digital signal processer (DSP) 308, amplifiers 310 (e.g., line drivers), a multiplexer and modulator 312, an input-output filter 314, carrier amplitude comparators 316, a multiplexer and demodulator 318, and a power supply 320. The data 300, and 306 may be acquired and processed by the digital signal processor (DSP) 308. The DSP 308 may manage the sensor data and include data filtering, gain, and offset. The data is amplified via the amplifier 310A and provided to a multiplexer and modulator 312. The multiplexer and modulator 312 generate frequency modulated carrier signals that are then amplified via amplifier 310B and provide to the input-output filter 314. In some embodiments, the multiplexer and modulator 312 is a modified asynchronous digital subscriber line (ADSL) type broadband multiplex and modulation system. As mentioned above, the DHU 118 also includes the power supply 320 that may provide power to the sensors 120, actuators, and other components of the DHU 118.
The three carrier signals described above each carry identical data and provide redundancy and an ability to cope with a wide range or motors and cable types, as the different carrier frequencies are affected differently by the motor parasitic capacitances and the power cable capacitances. The three carriers signals are multiplexed (e.g., via multiplexer and modulator 312) and, as described above, are transmitted to the surface across the capacitive effect 212 inherent in the motor windings (of the ESP motor and via the 3-phase power cable 112. Advantageously, as the data is identical in all three power phases, a partial or total failure of up to two of the phases does not prevent the sensor data from reaching the surface. Consequently, the data measurement system described herein provides immunity to ground faults at the motor or the surface. The carrier signals are provided from the input-output filter 314 to the ESP motor and, as described above, are transmitted via capacitive connections 212 across the windings of the ESP motor and onto the 3-phase power cable 112. As described above, the DHU 118 is capacitively coupled to the Y-point 210 of the ESP motor 201. In some embodiments, there is an additional capacitive coupling between the output of the DHU transmitter circuitry and the Y-point of the ESP motor to prevent the DC offset from affecting the transmitters. Additionally, the RMS or peak-to-peak amplitudes of the carrier signals are monitored and measured at the surface (e.g., via comparators 316). As described herein, the monitoring of the amplitudes of the carrier signals may provide information regarding the health or issues of each phase of the 3-phase power transmission to the ESP motor 201.
In some embodiments, as mentioned above, an additional frequency modulated carrier signal is used to carry control data between the surface and the DHU 118. The control data carrier signal may be transmitted on the 3-phase power cable 112 across the capacitive effect 212 inherent in the motor windings via the connection to the Y-point 210 of the motor 201 and across the capacitive coupling (protecting the DHU transmitters from DC offset at the ‘Y’ Point) to the DHU 118. In such embodiments, the control data carrier signal may be demodulated (e.g., by demodulator 318) to obtain control data 322. In some embodiments, the multiplexer and modulator 318 is a modified asynchronous digital subscriber line (ADSL) type broadband multiplex and modulation system. The control data may include commands for adjusting the parameters of the DHU 118 and performing remedial diagnostics.
FIG. 4 depicts a schematic diagram of the SU 122 in accordance with an embodiment of the present invention. As shown in FIG. 4, the SU 122 includes output filters 402, input-output filters 404, AC supply voltage 406, amplifiers 408 (e.g., line drivers), voltage dividers 410, multiplexer and modulator 412, multiplexer and modulator 414, carrier amplitude comparators 416, and a DSP 418. Additionally, the computer 124 mentioned above is coupled to the SU 122. The SU 122 is connected to AC voltage 406 that provides power to the ESP 110 and, in some embodiments, to the DHU 118 via the 3-phase power cable 112. As mentioned above, the SU 122 may be an enclosure having the components described below and may reside inside the controller 114 for the ESP 110. In some embodiments, the SU 122 may include serial interfaces and network interfaces (e.g., TCP/IP interfaces) for connection to external networks.
The SU 122 receives data 400 (e.g., sensor data received from the DHU 118) via the carrier signals transmitted over the 3-phase power cable 112. In some embodiments, the data 400 may include, for example, two temperatures, two pressures, three vibrations, four differential pressures, three voltages (e.g., Y-point voltage and power supplies). In some embodiments, as mentioned above, the data 400 may be updated every second, every two second, every three seconds, every four seconds, or every five seconds or greater. Advantageously, as mentioned above the sensor data 400 is replicated on each line of the 3-phase power cable providing redundancy in the event that of one or more lines fail Additionally, as mentioned above, control data 401 may be transmitted from the SU 122. The SU 122 may be connected to the lines of the 3-phase power cable 112 by direct connection or via clip-on coupling transformers. Additionally, as described herein, the SU 122 may transmit command data to the DHU 118.
Each phase of the incoming carrier signals may be received and filtered by the output filters 402 and provided to the voltage dividers 410. Additionally, the carrier signals are received and filtered by the input-output filter 404. After the voltage dividers 410, the carrier signals are amplified (via amplifiers 408A, 408B, and 408C) and provided to carrier amplitude comparators 416. The carrier amplitude comparators 416 may output phase condition data based on the amplitudes of the carrier signals to the DSP 418. The phase condition data may enable determination of the location of cable or phase fault. The relative amplitude levels recovered at the SU 122 provide a proportional amplitude/distance from the surface, thus enabling determination of the location of a failure. For example, if the amplitude of the carrier signal on phase B is 25% of the amplitude of the of phases A and C, then evaluating the source impedance of the phase B carrier signal will provide a distance from the surface where the amplitude reduction took place and, thus, where in the failure occurred.
The carrier signals are also received and filtered by input-output filter 404, amplified via amplifier 408D, and then de-multiplexed and demodulated (e.g., by de-multiplexer and demodulator 414) to extract the sensor data from the carrier signal. In some embodiments, the de-multiplexer and modulator 414 is a modified asynchronous digital subscriber line (ADSL) type broadband multiplex and modulation system. The sensor data is then amplified via amplifier 408E and provided to the DSP 418. The sensor data may then be provided to the computer 124 for analysis. The computer 124 may display the sensor data in various formats for viewing and evaluation by a user of the computer 124. The computer 124 may include, for example, carrier amplitude data analysis software, sensor data logging and analysis software, and other software. Additionally, in some embodiments, the data may be communicated to external computers or networks via serial interfaces or network interfaces of the SU 122.
Additionally, in some embodiments control data may be provided from the computer 124 to the DHU 118. In such embodiments, the frequency modulated carrier signal for the control data is generated via the modulator 412 and then amplified via amplifier 408F. In some embodiments, the modulator 412 is a modified asynchronous digital subscriber line (ADSL) type broadband multiplex and modulation system. The amplified control data carrier signal is transmitted through the input-output filter 404, on to the 3-phase power cable 112 to be received by the DHU 118 (order of things happening). Additionally, in some embodiments the command data may include control data for well components below the ESP 110, such as solenoid and motor drives. Moreover, such components may be powered by connecting to the Y-point of the motor of the ESP 110.
In some embodiments, the command data carrier signal is a 160 kHz carrier signal and may be modulated as direct digital data or as FSK data. Here again, side bands may be developed that are separated by about 16 kHz in the carrier pass-band spectrum. The control data is extracted from the connection at the Y-point of the motor of the ESP 110 and provided to the DHU 118.
In some embodiments, the SU 122 may also include a power supply to provide power in the event that the 3-phase power to the ESP 110 is turned off and the ESP 110 is not running. In such embodiments, the power supply may be a DC power source on all of the power phases and may be isolated by current trips or isolators to ensure protection against ground faults or line breakages in the phases of the 3-phase power cable 112. Thus, the data measurement system described herein may be able to provide sensor data in the event of a full phase fault or even two phase faults. In some embodiments, the SU 122 may provide low voltage DC power to the sensors of the DHU 118 even if the ESP 110 is shutdown, and the DC power may be pass through the motor windings of the ESP motor and be received by the DHU 118 as a normal power supply.
The timing granularity of the carrier signals may be controlled by the clock speed of the microcontrollers 504, thus determining the absolute accuracy of the deviated carrier frequency. For FSK modulated carrier signals having binary logic values, the absolute accuracy may not be a primary consideration. In other embodiments, the microcontrollers 504 may be clocked to higher speeds (e.g., up to 25 MHz) if finer resolution or higher carrier frequencies are used.
The carrier signals 508 are output from each microcontroller 504 and provided to low-pass filter and gain circuits 510. In some embodiments, the carrier signals are synthesized as square wave frequencies and are filtered to create sinusoidal waveforms. The low-pass filter and gain circuits 508 may receive gain control signals from the supervisory microprocessor 500. The configuration of the gain control signals may be received via the command data transmitted from the SU 122. The gain control signals may enable adjustment of the amplitude of the individual carriers. The filtered carrier signals 512 are multiplexed with a multiplexer 514 and the multiplexed signal 516 is coupled to the transmission interface via an amplifier (e.g., line driver 518).
As mentioned above, command data may also be transmitted via another carrier signal from the SU 120 to the DHU 118. FIG. 6 depicts decoding of the command data carrier signal in accordance with an embodiment of the present invention. The command data carrier signal 600 may be provided via a line interface to a band-pass filter 602. The command data carrier signal 600 is extracted via the band-pass filter 602 and provided to a phase-locked loop 604. The phase locked loop 604 may demodulate the received control data. The demodulated control data is then provided to a supervisory microcontroller 606 for further processing. For example, commands from the control data may be provided to the appropriate component, e.g., a sensor, actuator, or other component, for execution of a command. The components illustrated in FIG. 6 may be implemented in the components of the DHU 118 described above, such as the DSP 308.
FIG. 7 depicts a process 700 for generation and transmission of sensor data in accordance with an embodiment of the present invention. Initially, sensor data may be received from various sensors (block 702). As described above, the sensor data may include for example, two temperatures, two pressures, three vibrations, four differential pressures, three voltages (e.g., Y-point voltage and power supplies), and carrier amplitude levels. Next, the sensor data is encoded in three frequency modulated carrier signals (block 704). As described above, the signals may be modulated to three separate carrier frequencies separated by, for example, 32 kHz guard bands. Thus, in some embodiments the three carrier signals may be modulated to frequencies of 64 kHz, 96 kHz, and 128 kHz. Next, the three carrier signals are multiplexed (block 706). The multiplexed carrier signals are shunted across each motor winding of a 3-phase ESP motor via a capacitive coupling (block 708). The multiplexed carrier signals are transmitted from the DHU on each phase line of the 3-phase power cable coupled to the ESP motor (block 710). It should be appreciated that other actions used in the generation and transmission of sensor data, such as amplification, filtering, and other signal processing may also be performed, as described above in the discussion of the DHU 118.
The transmitted carrier signals are received at the SU on each line of the 3-phase power cable (block 712). The carrier amplitude data for each carrier signal may be extracted from the multiplexed carrier signals (block 714). The multiplexed carrier signals are also decoded, e.g., demodulated (block 716), and sensor data is extracted from the carrier signals (block 718). Next, the extracted sensor data and amplitude data is provided to a computer coupled to the SU for further analysis (block 720). For example, as described above, the location of line or phase faults may be determined from the comparisons of the carrier signals' amplitude data. It should be appreciated that other actions used on the receiving and decoding the carrier signals, such as amplification, filtering and other signal processing may also be performed, as described above in the discussion of the SU 122. Additionally, other carrier signals transmitted from the SU to the DHU, such as a control data carrier signal, may be generated and transmitted in a manner similar to that described above, with the generation and transmission occurring at the SU 122 and the receiving and decoding occurring at the DHU 112.
Although embodiments described above may refer to three carrier signals for transmission of sensor data and a fourth carrier signal for transmission of control data, it should be appreciated that more or fewer numbers of carrier signals may be used with the techniques described above. For example, in other embodiments five, six, seven, eight, or more carrier signals may be used. Such additions may be performed to increase update rate, add redundancy or both. Additionally, more or fewer sensors may also be included in the data measurement system described above, with a corresponding increase or decrease in the sensor data received at the DHU and transmitted to the SU.
In some embodiments, a non-isolated downhole electronics power supply may be used in the ESP system described above. As described further below, the power supply may provide DC power sourced from the 3-phase ESP motor star point (e.g., the Y-point 210 described above). In some embodiments, the power supply may receive a 30-40 V DC input voltage and provide regulated DC output voltages of 5 V (at 0.5 A) and 24 V (at 2.0 A). In such embodiments, the power supply may provide 10 W of DC output power and may not include any DC output isolation. Advantageously, the power supply may be compatible with low frequency FM modems signaling via the input power line.
In some embodiments, the power supply includes one or more very low frequency (VLF) input filters that incorporate over-voltage protection. As will be appreciated, such VLF input filters may admit low voltage DC power. Additionally, the input impedance of the front-end input filter may be “high” over the signal bandwidth of a communications modem coupled to the power lines such that signal propagation is not attenuated. Moreover, the input impedance may be yet “higher” over the 30-70 Hz high voltage AC power spectrum, such that AC power is rejected with a residue of no more than a fraction of a volt transmitted though the input filter to the downhole electronics power supply DC input.
With the foregoing in mind, FIG. 8 depicts an input filter and buck step-down regulator circuit 800 having over-voltage protection for a non-isolated downhole electronics power supply in accordance with an embodiment of the present invention. The circuit 800 includes a VLF input filter 802, a +24 V DC buck step down regulator 804, and a +5 V DC buck step-down regulator 806. As shown in FIG. 8, the circuit 800 includes an input 808 to a communication modem filters interface and an input 810 to a power source (e.g., the Y-point 210 of the ESP motor described above). The circuit 800 includes a ground 812 via earth, production tubing, or both. The outputs from the circuit 800 include a +24 V DC output 814 and return 816, a +12 V DC output 818 and return 820, and a 0 V output 822. The circuit 800 includes a DC power star point 823.
The VLF input filter 802 includes a second order LC filter with a non-dissipative damper. In some embodiments, the VLF input filter 802 may achieve a −3 dB corner at 0.3 Hz and around −80 dB attenuation at 30 Hz, thus transmitting at no more than about 0.5 V peak AC if subjected to 5k V peak sine at that frequency. In such embodiments, the input filter inductor may shunt 3 Hz communications signals with an inductive reactance in excess of 1 k ohm. As shown in FIG. 8, the input filter 802 includes an input filter inductor 824 (L1) and capacitors 826 (C1 and C2). Additionally the input filter includes a non-dissipative damper that includes resistor 828 (R1) and capacitor 830 (C3). The input filter 802 also includes a second input filter inductor 832 (L2) and capacitors 834 (C4 and C5). In some embodiments, the second input filter inductor 832 may be a high frequency ferrite cored component that may prevent the switching regulators from conducting high frequency interference back to the power line and the modems. Additionally, the second input filter inductor 832 may prevent any external high frequency interference from being conducted into the power supply inputs. In some embodiments, the inductor 824 (L1) may have an inductance of 64 H, the capacitors 826 (C1 and C2) may have a capacitance of 2200 uF, the inductor 832 (L2) may have an inductance of 250 uH, and the capacitors 834 (C4 and C5) may have a capacitance of 100 uF.
As mentioned above, the power supply having the circuit 800 draws DC power input from the star point of the ESP motor but remains serviceable in the event of a failure of one of the three phases. During such a failure, significant levels of 30-70 Hz AC may be present on the DC power input. In some embodiments. As specified, such components may pass DC and achieve a 0.3 Hz corner frequency with the stop-band producing around −80 dB attenuation at 30 Hz, such that unwanted 30 Hz 5 kV peak AC received at the power input is rendered to a residual of only 0.5 V peak superimposed on the desired DC input to the buck step-down regulators 804 and 806.
The input filter 802 also includes unidirectional transient voltage suppressors 836. The transient voltage suppressors 836 may protect the switching regulators of the circuit 800. For example, as shown in FIG. 8, one of the transient voltage suppressors 836 may be placed in parallel with the input filter capacitors 826 to prevent the input voltage from turning negative in the event of a high voltage AC event and to prevent a positive transient voltage from exceeding about +50 V.
As mentioned above, the circuit 800 includes a +24 V buck step-down regulator 804 and a +5 V buck step-down regulator 806. Each of the regulators 804 and 806 may draw current from the common input filter 802, but each regulator regulates independently of each other. Advantageously, as described below, the design of each regulator 804 and 806 may be similar to reduce design cost. In such embodiments, the differences between the regulators 806 and 806 may include different output current limiter value settings and different feedback factors to achieve the different outputs (e.g., +5 V DC and +24 V DC) from each regulator. The buck regulators 804 and 806 may be operated in continuous (inductor) conduction model, such that the DC output current ripples with a shallow triangle wave at the higher output levels. Although the input currents to the circuit 800 pulsate, the input filter 802 is used to average the pulsating input currents.
As will be appreciated, the +24 V buck step-down regulator 804 includes a pulse width modulation (PWM) switch 838, a diode 840, an inductor 842, a capacitor 844, and resistors 846. The regulator 804 also provides feedback 848 for control of the regulator 804. Similarly, the +12 V buck step-down regulator 806 includes a PWM switch 850, a diode 852, an inductor 854, and a capacitor 856. Here again, the regulator 806 may provide feedback 858 for control of the regulator 806. In some embodiments, the buck power regulators may include an L296 switching regulator manufactured by STMicroelectronics of Geneva Switzerland. A LM257gHV switching regulator manufactured by Texas Instruments of Dallas, Tex., or a LT1074HV switching regulator manufactured by Linear Technology of Milpitas, Calif. Such embodiments may limit the input DC voltage to below 40 V via the transient voltage suppressors and maintain the DC input voltage above 30V to ensure adequacy duty cycle headroom for the 24 V DC regulator.
Alternatively, in some embodiments, the power supply may include a multiple output buck step-down regulator. FIG. 9 depicts a circuit 900 of a multiple output buck step-down regulator in accordance with an embodiment of the present invention. As shown in FIG. 9, the circuit 900 includes a DC input 902 and a return 904. The circuit 900 also includes a +24 V DC output 906, a +12 V DC output 908, and a 0V output 910. As will be appreciated, the circuit 900 includes a PWM switch 912, a diode 914, and an inductor 916, a capacitor 918, a resistor 920, and a diode 922. The circuit 900 further includes capacitors 924. The inductor 916 may have a second winding and rectifier used to provide an auxiliary output. However, as will be appreciated, power available from the auxiliary output may be limited less than 20% of the main output power and will also vary with the 5 V output power demand. The circuit 900 may provide feedback 926 for control of the multiple output buck step-down regulator.
Where H is the transfer function, Vo is the output voltage, Vi is the input voltage, L is the inductor of the inductor 1004, Rd is the resistance of the resistor 1008, and C is the capacitance of the capacitor 1006.
As shown above, inductor values of a few mH may result in the filter corner frequency rising above 30 Hz, and an inductor value of 1 mH would result in the corner frequency exceeding 70 Hz with no attenuation benefit. Thus, the inductance value may only be reduced by a few mH before the AC residue amplitude exceeds the DC power supply voltage, subjecting electrolytic capacitors used in the filter to reversed polarity on the negative half cycles and resulting in capacitor failure.
In view of the foregoing discussion, FIG. 12 depicts a circuit 1200 having a two stage switching regulator for a non-isolated downhole electronics power supply in accordance with an embodiment of the present invention. In some embodiments, the circuit 1200 may operate from a DC power input of around 70 V and may operate up to a DC power input voltage of 100V or higher, 200V or higher, 300V or higher, and so on. As described below, the power input is accepted via a steering diode and is thus capable of operating from AC input power or a combination of AC and DC input power.
The circuit 1200 includes an input filter 1202 (e.g., an LC filter), a switching pre-regulator 1204, a +24 V DC buck step-down regulator 1206 and a +5 V buck step-down regulator 1208. The circuit 1200 includes an input 1210 to a communication modem data interface and an input 1212 to a power source (e.g., the Y-point 210 described above). In some embodiments, the input 1212 may receive +70V DC and 30-70 Hz AC. The circuit 1200 includes a ground 1214 via earth, production tubing, or both. The outputs from the circuit 1200 include a +24 V DC output 1216 and return 1218 and a +12 V DC output 1220. The circuit 1200 includes a DC power star point 1222.
As shown in FIG. 12, the circuit 1200 includes a steering diode 1224, and the input filter 1202 includes an inductor 1226, and a capacitor 1228 that may serve as a hold-up reservoir. The input filter 1202 may block backward conducted emissions of interference from the switching regulators to the input power interface. Additionally, the filter may also smooth any rapid input voltage variations that the pre-regulator 1204 control loops may be otherwise incapable of tracking. The input filter 1202 may also prevent external noise from entering into the switching pre-regulator 1204. The circuit 1200 also includes a non-dissipative damper that includes resistor 1230 and capacitor 1232. As mentioned above, the circuit 1200 includes a switching pre-regulator 1204 that includes a PWM switch 1234 (e.g., a δ1 PWM low side switch) and a transformer 1236. In some embodiments, the switching pre-regulator 1204 may include an isolated single switch forward converter. The circuit 1200 further includes a diode 1238, an inductor 1240, and a capacitor 1242. The circuit 1200 may also include multiple transient voltage suppressors 1244.
The switching pre-regulator 1204 may accept a wide range of input voltages and may generate an intermediate regulated DC voltage 1245. In some embodiments, the intermediate regulated DC voltage is about 35 V. The intermediate DC voltage provides a stable DC input voltage for the buck step-down regulators 1206 and 1208. Thus, the risk of excessive voltages being applied to the buck step-down regulators 1206 and 1208 is minimized, and the effect of line voltage variations on the output regulators control loops is also minimized. Thus, in some embodiments the control loop of the switching pre-regulator 1204 may be mainly performing line voltage regulation. The gate of the power switches of the switching pre-regulator 1204 may be driven directly from the PWM driver relative to the 0 volts power return. In some embodiments, a line voltage may be applied feed-forward to the pre-regulator 1204 control loop or the control loop may be operated with current mode control.
As shown in FIG. 12, the regulators 1206 and 1208 may be isolated single switch step-down regulators. The +24 V DC buck step-down regulator 1206 includes a PWM switch 1246 (e.g., a δ2 PWM switch), a diode 1248, an inductor 1250, and a capacitor 1252. Similarly, the +12 V DC buck step-down regulator 1208 includes a PWM switch 1254 (e.g., a δ3 PWM switch), a diode 1256, an inductor 1258, and a capacitor 1260. The PWM control circuits of the regulators 1206 and 1208 may run directly from the internal intermediate DC (e.g., 35 V DC) described above, and the high side power switches of the regulators 1206 and 1208 may also operate from the same internal DC. The PWM control circuit of the pre-regulator 1204 may also include a start-up power supply derived from the power input interface. After starting, the control circuit may then be powered by the internal intermediate DC voltage described above or, in some embodiments, an auxiliary winding on the pre-regulator transformer.
Thus, if the input voltage approached about 1100 V the pre-regulator power switch state could never become fully enhanced. In such instances, the pre-regulator may suffer massive commutation losses as a result of the power switch state being confined to a dynamic linear mode for 3% of the switching period and off for the other 97% of the switching period. Because the flux reset process of an isolated forward convertor subjects the power switch to a voltage in excess of the input power line voltage, a margin may be provided when selecting the power switch voltage rating.
In some embodiments, the pre-regulator may include a MOSFET manufactured by IXYS Corporation of Milpitas, Calif., International Rectifier Corporation of El Segundo, Calif., or Toshiba Corporation of Tokyo Japan. Such embodiments may operate with a line voltage up to about 600 V. In some embodiments, the pre-regulator may include a SGL40N150DTU IGBT manufactured by Fairchild Semiconductor of San Jose, Calif., and such embodiments may provide for higher line voltages. In other embodiments, if the pre-regulator operates at higher AC voltages in the region of several kilovolts, then the pre-regulator may include a three-phase step-down transformer and rectifier.
Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as examples of embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed or omitted, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims. Headings used herein are for organizational purposes only and are not meant to be used to limit the scope of the description.
As used throughout this application, the word “may” is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). The words “include”, “including”, and “includes” mean including, but not limited to. As used throughout this application, the singular forms “a”, “an” and “the” include plural referents unless the content clearly indicates otherwise. Thus, for example, reference to “an element” includes a combination of two or more elements. Unless specifically stated otherwise, as apparent from the discussion, it is appreciated that throughout this specification discussions utilizing terms such as “processing”, “computing”, “calculating”, “determining” or the like refer to actions or processes of a specific apparatus, such as a special purpose computer or a similar special purpose electronic processing/computing device. In the context of this specification, a special purpose computer or a similar special purpose electronic processing/computing device is capable of manipulating or transforming signals, typically represented as physical electronic or magnetic quantities within memories, registers, or other information storage devices, transmission devices, or display devices of the special purpose computer or similar special purpose electronic processing/computing device.
a buck step-down post-regulator coupled to the switching pre-regulator and configured to receive the first DC voltage, the buck step-down post-regulator configured to provide a second output DC voltage and a third output DC voltage, wherein the second output DC voltage is less than the first DC voltage and the third output DC voltage is less than the second output DC voltage.
a processor configured to extract sensor data from the demodulated carrier signals.
a modulator configured to provide a frequency modulated control data carrier signal, wherein the surface unit is configured to transmit the control data carrier signal across the capacitive coupling and to the downhole unit via the 3-phase power cable.
4. The data measurement system of claim 3, wherein the frequency modulated control data carrier signal comprises a carrier signal at 160 kHz.
a plurality of carrier amplitude comparators configured to extract carrier amplitude data from the at least three carrier signals.
6. The data measurement system of claim 1, comprising a computer coupled to the surface unit, wherein the surface unit transmits sensor data to the computer.
7. The data measurement system of claim 6, wherein the surface unit receives control data from the computer.
8. The data measurement system of claim 1, wherein the surface unit is housed in an enclosure of a controller for the ESP.
9. The data measurement system of claim 1, wherein the surface unit is coupled to an AC voltage source.
10. The data measurement system of claim 1, wherein the at least three frequency modulated carrier signals comprises a first carrier signal at 64 kHz, a second carrier signal at 96 kHz, and a third carrier signal at 128 kHz.
11. The data measurement system of claim 1, wherein the modulator coupled to the processor is configured to generate the at least three frequency modulated carrier signals via frequency shift keying.
12. The data measurement system of claim 1, wherein the plurality of sensors comprises of: a temperature sensor, a pressure sensor, a vibration sensor, and a voltage sensor.
13. The data measurement system of claim 1, wherein the plurality of sensors comprises a flow meter comprises a differential pressure sensor having a plurality of differential pressure transducers.
20120037354 February 16, 2012 McCoy et al.
Partial International Search Report for International Application No. PCT/IB2014/002065 mailed Jun. 26, 2015.
Completed International Search Report and Written Opinion for PCT/IB2014/002065 dated Oct. 23, 2015.


Because the Special-II has only two knobs—not enough for all that (and, I already eliminated any possibility of using "push-pull" pots when I converted to dual-concentric pots), I must use toggle switches. That made me nervous (drilling holes; looking too DIY, "Frankenstein").
Those are perfect for my goal, to keep my guitar looking relatively stock. I found switches to implement all those tone-wiring mods. That's the entire "Jimmy Page" wiring (minus "serial humbuckers" by itself, which I don't like the sound of anyway), plus a single-coil sounding "parallel-coil.").
This mod can be done with the Special-II's original 1-conductor (plus ground) leads. However, it's better to have 4-conductor leads. Because of that, I did the next step first.
Reminder: it may may have hum with the Special-II's 1-conductor pickups. More so with unshielded jumper wires laying around. But, it will give you an idea of what it sounds like compared to normal wiring.
This is required for the next mod (coil wiring switches). As mentioned in the previous step ("Al King tone"), this will also reduce hum when using OOP humbuckers. (I did this step first.).
This mod requires 4-conductor pickups (previous step).
You can use a 3-position switch to have both "single-coil" types of wiring (I did). Or, use a 2-position switch for just one type.
This can also be implemented with two switches (as I did, to control each pickup individually). Or, use a single 4PDT switch to control both pickups in tandem.
The next post shows the "Al King tone" mod. Coil switching turned into three installments, beginning a little further down this page. That's followed by a variation of coil switching which includes switchable 50s/modern tone wiring (but remains just a diagrammed idea).
 I found these Taiway switches at LoveMySwitches (US). They were very supportive. I showed them what I wanted to do with a 3-position 4PDT. They added it to their inventory. (If you wanted black or gold finish, you could talk to them.).
I also saw a nice selection (including black and gold finish) at BanzaiMusic (Germany). I don't think they had the 4PDT switch. Taiway's web site lists regional representatives who should be able to help locate sellers in other regions.
 The so-called "Albert King tone" manipulates only the neck's hot and ground wires. A 4-conductor lead carries two separate grounds: the coil ground (the green wire, per Seymour Duncan's color code), and the pickup frame's ground (plus shield). The Special-II's humbuckers combine those two grounds into one.
The problem: the OOP portion of "Al King tone" requires the 4-conductor's black & green wires be reversed (Seymour Duncan color codes for hot and coil-ground, respectively). When you do this with your 1-conductor lead, your shield becomes part of the "hot" wire. This will result in hum when you touch the strings, or are near noisy electrical devices.
The solution is to replace the leads with 4-conductor (plus ground) wire. That's not hard to do (see my other mod: convert Special-II pickups from 1-conductor to 4-). But, 1-cond isn't terrible either. It could be worth implementing before delving into 4-conductor wiring. The switch will work either way. It could be a "baby step" along the way to doing everything.
 After converting your pickups to 4-conductor, you might feel comfortable swapping magnets, or creating "hybrid" pickups. See the 1-conductor to 4- mod, Post #1, footnote 3.
PDF version attached as "Albert King tone - original & 3-position example.PDF"
The original diagram uses a 2-position push-pull pot (down: normal wiring, up: "Al King tone"). I modified that to use a 3-position toggle switch (OOP-only in the middle position.). OOP by itself is a slightly different sound, and commonly used. It seemed worth having.
That diagram shows 1) out-of-phase humbuckers (the diagonal blue wire across the switch), and 2) humbuckers wired in series (the neck's black wire goes to the bridge's black wire. If OOP was removed from that diagram, the neck's green wire would go to the bridge's black wire, which constitutes serial wiring.).
I'm still unclear what makes this serialized. I believe both pickups are entirely serialized when the pickup selector is in the neck position. However, when both pickups are engaged it appears to be a variable serial circuit, depending upon each pickup's volume. (That could explain why this wiring sounded better to me than when I tried to combine a more obvious serial-humbucker wiring diagram with an OOP diagram.).
If you've performed either of my two previous mods, you should have a diagram of your current wiring.
Note: Using the Special-II's original 1-conductor pickup leads?
If you haven't converted your 1-conductor leads to 4-conductor, with one caveat you can use your original one-conductor pickups. You'll use your neck pickup's single hot wire (mine was white), and its bare ground wire. Translate your wires into the diagram's black (hot) & green (coil-ground), respectively.
Diagrams: Dual-concentric (2-vol, 2-tone) + 4-conductor pickups + "Al King tone"
Diagrams: Original "master" wiring + 4-conductor pickups + "Al King tone"
Normal-length levers may be better if you need to manipulate the switch mid-song. But, for a couch guitar that I want to learn with, trying to keep it looking original/low-profile, I really like that stubby lever(!).
This mod can be done with either of those switches. It's up to you whether you want the extra choice of OOP-only in the middle position. (I used the 3-position 4PDT.).
This was a surprisingly challenging topic. First, the Taiway switches don't come with a finish washer. They come with a keyed washer to use underneath to prevent the switch from rotating. And a star washer. I didn't use either. (You definitely wouldn't use the star washer on the guitar's finish side. I think these parts are for installing the switch in a box or on a panel.).
Second: the next mod (coil switching) can use two switches side-by-side. That leaves very little room for finish washers.
Third: washers you find at the hardware store are thick, load-bearing. Even the smallest ones stand out a bit much (and might not fit together with two switches mounted side by side, which happens in the next mod).
Fourth: I was tempted to not worry about this topic until I get to the next mod. But, using a larger washer (that you intend to replace with a smaller) might leave an imprint or scratch on the guitar's finish (called "raccoon eyes").
Eventually I discovered "shim" washers. They're very thin, and not wide (not much exposed). But, shim washers are hard to find. They're specialized for precision applications (gunsmiths, hobbiests?). I found some stainless shim washers on Amazon. They're only 0.016" thick and 0.3775" wide. They're nicely proportional to the switch's hex nut (.06" thick; .313" across the flats; .357" across the peaks.). More importantly (for the next mod): they'll look proportional with two switches installed side-by-side.
Note: I have some spare shim washers. If you're doing this mod in the US, I can help you out (use the forum's private message feature to contact me).
LoveMySwitches sells a pack of 10 "flat toggle washers - mini size." I have some. They are 0.033" thick, 0.470" OD, 0.249 ID. That's smaller, thinner, better-fitting than anything I found at the hardware store.
But, the DPDT switch housing is 0.46" wide. So, these washers will almost touch if you use two switches side-by-side (which is possible in the next mod). That might not look right. Also, I think they're nickle (or zinc) plated—which means you can't file/redimension them (removing the finish would lead to rust.).
Choose the best size washer (enlarge the hole using a hand reamer, if necessary).
Superglue the washer to the head of a long screw.
Lock the threaded end of that screw into a drill chuck.
Spin the washer against a file to reduce the outside diameter.
Polish the outer edge using 400, 800 & 1200 sandpaper.
Use acetone to "unglue" the washer from the screw head.
Superglue that same washer flat against a small block of wood.
Use that block as a "sanding block" against a file laying flat on a table.
When it's thin enough, polish using 400, 800 & 1200 sandpaper.
That sounds tedious. But, if you want a right-sized washer, and can't find (or afford) shim washers, you can make your own. (Remember: you can't do this with zinc-plated washers. It will expose bare steel, which will rust. It must be stainless.).
Remove the knob and "Rhythm/Treble" faceplate (don't remove the pot and switch yet).
Put a piece of masking tape on the guitar's finish between those two controls. (Be generous, cover a lot of finish. Protect it from scratches while you work. Tape's cheap.).
Reinstall the knob and faceplate.
Trace their profile onto the tape.
Unsolder and remove the pots and 3-way pickup selector from the cavity.
Use a ruler to draw a centerline from neck (pot) hole to 3-way hole.
Mark the middle of that line (between the outline of knob and faceplate).
IMPORTANT: Turn your pots to zero before unsoldering them. Any other location could result in a scratchy sounding pot. I've read that the heat could damage the disk insie the pot. "Zero" means zero on your knob (no sound), which is also zero resistance in the pot (all the signal going to ground instead of the jack). In this location, any scratching sound wouldn't be obvious because it's going to ground.
Hint: masking tape can be more adhesive than necessary. I've been pressing it against my pant legs before using it. (This probably isn't a problem for the Special-II's thick poly finish. But, other/vintage guitars might be damaged by the too much "sticktoitiveness."
NOTE: Another reason it may be useful to do the dual-concentric mod first: this switch will be centered between the knob and "Rhythm/Treble" faceplate. If you ever change your knobs to a different size, the switch may not be centered. Since the dual-concentric mod forces you to consider your choice of knobs, it could be better to do that first. (The knob I used was almost the same diameter as the factory "speed knob." In that case it won't matter. But, if you opted for mini knobs, that would affect where you drill this hole).
The switch's threaded bushing is 0.238" diameter (0.350" tall). You might be tempted to drill a 1/4" hole. However, drilling a hole in a guitar isn't as simple as you'd think. Ordinary (round) drill bits can grab/lift/chip the thick poly finish off the wood. They can also gouge a chunk of wood out (especially if you're trying to enlarge an existing hole).
Forstner and "(FISCH) brad-point twist bits" are used by woodworkers for this kind of work. These bits cut an outer edge first. (If you had an existing hole, you'd plug it with a dowel, then re-drill it with the bit. Using an ordinary round drill bit to enlarge such a hole can gouge chunks out, split the wood.).
Some people use a small acorn-shaped dremel bit (with wavy fins on its side) to grind the finish down to the wood—wide enough that the ordinary (round) drill bit won't grab it. Then use a ordinary (round) drill bit to drill the wood. (I've seen a more pointy version of this which looks more like a triangle than an acorn. I also saw people say they use "countersink" drill bits. Perhaps more for "dressing" the finish-edge of the hole, so it doesn't grab/hang upon the part inserted into it. The dremel bits would work for that too.).
A "step drill" is made for drilling holes.
Run an ordinary (round) drill bit in reverse to remove the finish before drilling into the wood (in forward). This is said to heat the finish, softening it. (I've also seen recommendations to use a hairdryer to do the same, with any of the above.).
My conclusions: 1) I don't want to spend $20 USD on a forstner bit. Plus, the shim washer doesn't have much width (to cover much beyond the hole). I need a snug, clean edge around the hole. I'd be nervous creating a hole in one shot might not have a snug, clean edge. 2) I don't have much dremel experience. I get a mental image of that acorn-shaped thing "skating" across the finish of my guitar. 3) I've used "step drills." They can be a little rough around the edges. But, more importantly, they aren't meant to drill a deep hole. By the time I got to the other side of the wood, the next "step" would be cutting into the first side.
Drill a 3/32" (0.094") pilot hole to help prevent the next steps from "drifting." (This drill bit is small enough that it shouldn't grab the finish. No need to run it in reverse first.).
Note: I used a punch to make an indentation before drilling. I thought this would help the hole start without the bit drifting. But, I didn't feel good striking my guitar. That might not be a good idea. But, that's what I did.
Drill a 11/64" (0.172") hole. This is one size smaller than the bit used in reverse. I.e., the finish will be removed slightly past what this bit could reach (and possibly lift/chip).
Use a reamer to enlarge that 0.172" hole approximately 0.066", until the switch fits snugly in the hole.
Because reamers are tapered, you won't get the same size hole on both sides. Since you want a tight fit at the finish-side of the guitar, you should ream the hole from the cavity side. (Go slow, and check the fit frequently. It doesn't take many twists.
When removing the reamer: don't rock it back and forth to wiggle it out. Instead, twist and let it work it's way out. I think I created some hexagonal indents, seen in the following photos.).
Also, the reamer's handle has a tendency to fall out. It could hit your guitar. Wrap some electrical tape on it so it won't slip out.
Because the hole will be tapered from the cavity side, you'll know you're close when the threaded bushing slips in from that side. At that point, continue reaming from the cavity side, but test the switch fitting through the hole from the finish side.
Don't force the switch in; don't wiggle it if it's tight, don't thread it into a tight hole. Remember: the hole is tapered. When you're that close to it slipping in, it's entirely the thick poly finish hanging on the threads. If you force it, twist it, push/pull hard, you could lift the finish off the wood (causing the same thing as what you tried to avoid with tedious drilling).
That may sound tedious, or overkill. I could have drilled a 1/8" (0.125") hole; ream that to 0.238. But, that's a lot of reaming. Or, I could have started with the 11/64" (0.172") hole. But, that could be large enough to chip or lift the finish. (I would have had to reverse-drill the finish first. But, then I wouldn't feel comfortable reverse grinding without a pilot hole to help keep it from "drifting".).
Which takes me back to the pilot hole: A larger pilot hole would definitely work better to hold the reverse-grind centered. But, whenever you enlarge an existing hole (in forward), these drill bits are more likely to grab and rip out a chunk of wood/surface, especially if the hole's size is closer to the bit you're using. (This is why it's so risky to use these bits to enlarge tuner holes. It's easy to split the headstock when the slightly larger bit "grabs" into the existing hole. The reamer you used here will be perfect for that job.).
That was my reasoning for how I did it. "Better safe than sorry."
Note: I think I see indications of the finish cracking/lifting. I think this was because I pushed/twisted/wiggled the switch when it was still tight in the hole (snagged against the finish. The above warning against that came to my mind as I started to do it. I didn't do it much.). The damage isn't much. But, I bet that was it. (In the next mod, I drilled two holes. Neither had that appearance.).
I've read that the finish edge should be beveled using a "countersink" bit so the finish won't "catch" on the part being inserted/removed. That's probably more important for bushings pressed tightly in (and could lift the finish when removed). That seems like a good idea in this case. The sharp edge feels like it's inviting a problem.
I accidentally bumped into the top of that bulge. (No big deal. I have leftover adhesive shielding. But, I thought I was being careful. That's how easy it is.). Tape your pickup wires back; maybe even put a kitchen spoon in front of them for protection. (If the dremel touches those for even a moment, you'll have another project to do.).
From the photo, it's hard to tell how much material I removed. The semi-circle on the cavity floor is where the bulge was.
After removing the finish from the cavity floor, the thickness of my guitar's front was just right for the length of the switch's threaded shaft (0.350" long). I will apply a square of adhesive shield over the newly-exposed areas. That should cause the switch to be at a perfect height. If the finish had remained on the floor of the cavity, the exposed switch threads would have been a little too short.
The steel tool removes material fast. The stone works slower; easier to control. The stone was good for making the bottom flat, and remove the finish from the floor of the cavity.
This photo shows what the cavity looks like (how much space you have) with the switch installed.
The only noteworthy thing about that photo: I rotated the neck pot counter-clockwise (from where it was in my dual-concentric mod, see the next photo.). A lug on the pot was touching the side of the switch (which is metal, grounded). I rotated the bridge pot too.
Hint: Your 3-way pickup selector is "cocked" a little (inside the cavity; i.e., it doesn't point to the ends of the cavity). That's so the lever travels along the same axis as your tailpiece. You can try to orient this toggle switch similarly. The next mod involves switches on the other side of the 3-way selector. That line (between 3-way and bridge knob) is almost square with the tailpiece. I.e., those switches travel the same axis as the 3-way.
I used that same jig for this project, adding the hole for this switch. Just line up the existing holes and mark the new one. Be sure to put masking tape on your finish or you'll scratch it. (Per the previous photo: I rotated the pots so their lugs face further away from each other.).
If you've done either of my first two mods, this step should be easy. There will be more soldering, in tighter spaces. But, for me, much less stressful than drilling a hole in my guitar.
If you haven't done my first two mods, you should read my hints/warnings about soldering in the dual-concentric mod, post #3, and 4-conductor mod, post #1. Items like these mini toggle switches are easy to destroy with heat. I talk about that issue, especially in the dual-concentric's 3rd post.
The key seems to be: use a solder iron that has enough watts to drive the tip, and heat the solder joint quickly. Low-power irons could cause you to sit there for 30 seconds, applying heat (which will melt the switch). You just want to touch the iron for 2-3 seconds. Don't think that the iron is suitable just because solder melts when it touches the tip. The problem with low-watt irons is that the item being soldered (the switch) will draw heat from the iron faster than it can be replaced. You end up heating the entire piece hot enough to melt solder. You don't necessarily want a hotter iron, but one that can react to heat loss and drive it back quickly. One that stays hot. (In the dual-concentric's 3rd post I show an inexpensive iron which has worked well for me. It's listed as a 50-watt, but draws 80+ when plugged. That kind of variable drive is what you want.).
It's also smart to "tin" the wires and switch lugs. (Give lots of time between tinning multiple lugs; or tinning and soldering a single lug. Heat could accumulate in the switch, making it hotter with each touch of the iron.). If both pieces are tinned (pre-soldered), you should be able to just hold the wire to the lug, heat the joint till it wets, and stop. (No need to apply solder while you do this.). Try to hold the wire steady for 4-5 seconds after you take the iron away. Don't blow on it to "help" it cool. That's how bad solder joints happen.
I used 22 gauge solid wire to make the connections. I like solid wire because it adds rigidity to the harness, creating a "skeleton," making it easier to transfer it in/out of the cavity. However, solid wire will weaken & break when flexed a few times.
However, this mod required so much rearranging, fitting, etc., that the solid wire made me nervous. You should probably use more stranded wire than I did. It's more forgiving. Solid is better for short, fixed connections. (The longer connections act like a lever upon the solid.).
I used 22 ga stranded wire to make "pigtails" where the pickup wires connect. That will be easier to solder to after installing the harness into the cavity.
Instead of pigtails, I could remove the harness from the jig, rest it half into the cavity, solder the pickup wires where they go. But, I anticipate replacing the magnets in my pickups, maybe other things. I think having pigtails will make it easier to work on the pickups without disturbing the harness.
I temporarily wired the harness to the pickup wires, and verified that it works.
It can be difficult guiding the pots and switches into their holes. There's not as much room for your fingers to shove things where they need to go. I used a small (jeweler) screwdriver to push pot shafts and toggle levers toward their holes.
The neck's black & green wires go to their respective switch pigtails.
The switch, where it connects to the bridge's volume pot.
The two pickup bare grounds.
The ground wire from the bridge bushing.
The next mod will unsolder some of this mod's wiring. After doing this mod, it seemed like it would be more efficient to do this and the next mod as one project. But, that would have been overwhelming. Drilling this mod's one hole was the most stressful part for me. The next mod will use two holes (almost zero room for error). Doing this mod by itself (and hearing it work) alleviates a lot of anxiety.
I'm not sure what the trade name is for that hardware. I believe I saw it called "dress ring," "finish ring," "knurled nut," or "knurled ring." The switch's thread is "1/4-40 UNS." I was unable to find one of these. I'm sure they exist. The problem is Google ("dress ring" returns wedding-related results.).
10.2. I think my 3-way pickup-selector's threads protrude too far. In the next mod (coil switches) I will use a washer (inside the cavity) to lower the 3-way.
This is probably due to me replacing the factory faceplate (mentioned in step 4 "positioning the switch"). The new faceplate is about half the thickness. Plus, the Special-II comes with a finish washer over the factory faceplate. From photos I've seen, higher-end Les Pauls don't have that washer. So, didn't use it when I installed the new faceplate. Those two factors probably make the 3-way's exposed threads look tall.
10.3. Since the photos show this, I'll mention it again: after the soldering step, I realized I should have oriented the switch 180 degrees so the "keyway" (a vertical slot in the threads) faces down. You'll get a slightly cleaner look doing that.
 I don't recall where I found the original "Albert King tone" diagram. A tineye image search produces many copies.
 When I converted my pickups to 4-conductor, I temporarily wired the "Al King tone" diagram. It sounded good. But, the diagram didn't look as clearly "serial" as others I'd seen. Since I wasn't confident in the diagram's pedigree (nor it's invocation of Albert King), I tried a different "serial humbuckers" diagram, and added OOP to it. That didn't sound as good to me. Being uncomfortable advancing the above diagram as "serial" (not understanding it), I asked on the forum if this diagram is indeed serial. It was confirmed to be.
 Wiring this with the Special-II's one-conductor pickup leads can cause hum. See Post #1, footnote 2.
South is screw side; north is slug side.
The White & Red wires are usually soldered together and taped for serial coil wiring.
Green is ground and Black is hot/Output.
 For datasheet and dimensional drawings, see the individual product pages at LoveMySwitches. See Post #1, footnote 1 for more resources, and the possibility for black or gold finish.
That page shows the seller's model number: Z9796.
If those pages disappear, it may be discoverable using the ASIN or model number. The Amazon seller is named "Small Parts:"
I think that's Amazon's own mega-merchandising—which might not be committed to selling this item (as an actual seller would be who is engaged in the business of precision hardware).
Something tells me that may not be a long-term place to find this washer.
Wow, thanks for the very cool detailed post.
I bought a cheap B.C. Rich Bich recently. it has a simple volume/tone/toggle and I intend to add 3 toggle switches and a set of GFS pickups that I already had. I am also adding a killswitch.
Personally, if I wanted to go that rout, I would use the Gibson 6 way switch diagram for the L6s. Switches are like 12 bucks on feebay.
I saw those. I thought the stubby toggle lever would stand out less (and be easier to actuate) than a knob. Plus, I would have to use toggles for the upcoming coil-switching mod. I think that wouldn't look right together.
Also, I never saw dimensions for that rotary switch. Space was a concern for me. I've seen the rotary's required cavity height is 1-5/16" (1.313"). That's 2x taller than the switch. The Special-II's cavity isn't very big. Just from the product photos, I'm sure that rotary switch consumes more sideways space too. That might be a problem.
The 4PDT toggle switch is 0.610" tall (in the cavity), 0.855" long, and 0.50" wide. That's a tight fit by itself.
EDIT: It occurred to me you might have been replying to @Riffster . Which brought to mind the (rather pricey) "freeway" 6-way pickup selector switch. (Stewmac has them.). That might fit over the toggle switches I'm doing. That might be an effective kill switch. Just knock the selector over to the other 3 positions. One could be dead. That would also leave 2 positions for something else.
That switch was what I initially planned to use. It seemed like a "free way" to get more choices without drilling holes. But, I read a couple people saying the switch can be fiddly. It doesn't reliably make connections. (I understood what that's like when I realized my own 3-way pickup selector was doing that.).
I have a freeway in an Ibanez I have. Once you get used to it, it's worth the price.
This post will modify my Special-II's humbucker wiring to include single-coil ("cut"), and parallel coils (which sounds like single-coil, while retaining dual-coil humbucking).
That is a 3-position DPDT (on-on-on) switch. Notice the staggered lug connections when the lever is in the CENTER position. (The grayed out diagram is a different type of 3-position switch called "center on," where all the lugs are connected in CENTER. Be sure to get the correct type.).
- In the DOWN position: the middle lugs connect to the top lugs. That's normal (serial) wiring: the red & white coil wires are connected, creating serial coils. (I.e., one coil's ground—the white—is connected to the other coil's hot: red.).
- The CENTER position is harder to understand.
Remember: the contacts are staggered. For me, the easiest way to think about it: both coil grounds (green & white) go to ground. But, only the north/stud's hot (black) goes to the volume pot. The south/screw's hot (red) goes nowhere. Therefore, the active coil is the north/stud coil.
That "cut" wiring is called "conventional" (at least, on that site).
Which coil should be active?
There is another type of wiring called "inside-out" ("alternative" on that site). It makes the south/screw coil active. This may produce more tonal difference, especially in the bridge position. For more info, see this 1728 page: "Coil Cut Switching" (archived). It also suggests mixing which coils are active (ex., north/stud in the neck + south/screw in the bridge).
Note: That page uses DiMarzio colors. I had trouble translating it into my wiring. I modified these two diagrams to use Seymour Duncan colors. These should help you translate the diagrams on that page to your wiring.
Before soldering the switches you can use jumper wires to experiment.
You might also consider using Seymour Duncan "Triple Shot" rings (two slider switches built into the humbucker rings). These let you easily experiment with those coil choices. See Mod #3 "Triple shot" + 50s/modern tone wiring. (That's a future mod I'll do. It could be done now using the wiring diagram in that post. It uses the same holes, but different switches: two-position 3PDT on-on.).
FWIW: If you didn't want "cut" (were happy with serial & parallel coils), you would use a 2-position DPDT (on-on) switch. It would work the same as above, without a middle position.
The following steps are almost identical to the previous "Albert King tone" mod. I'll only describe what's different. Be sure to read that mod for very important info which applies here too.
This post modifies the wiring which resulted from the earlier "Al King tone" mod.
The washers' size is much more important in this mod. I obsessed about that topic in step #3 of the "Al King tone" mod.
The only difference here is that I need two holes. I initially intended to place them side-by-side between the faceplate and knob. But, that looked too crowded. I'll go ahead and explain what I did up to that point.
This time I drew lines across the holes' top & bottom edges. That helped me see the centerline. (I put a pen inside the hole, pushed the ruler against it.). Reminder: Don't press too hard with the pencil. You could score the finish, leaving a visible indent.
However, the switches angle inward. The switches' bottoms (the lug area, at the top of the photo) is slightly wider, causing the levers to angle inward a little. (The holes need to be a little further apart than the levers suggest. In fact, the marks are a little further apart.).
If you put too much space between those switches, the finish washers will touch the faceplate or knob (although the knob will accommodate that because it will be suspended a little above the finish). Too little space: one switch won't fit in its hole. (Together these switches are 0.92" wide. The one I used in the "Al King tone" mod was 0.86" long. I.e., these switches, inside the cavity, will also be a little closer to the pot.).
In the previous ("Al King tone") mod I stressed keeping the hole snug to the shaft. In this mod, some play will probably be beneficial. Reaming a tenth of an inch further will provide a lot of adjustment within that limited space.
I drew the vertical centerline parallel to the tailpiece's axis. You can lay a ruler against the tailpiece bushings, lightly(!) trace the line, then work your way back from that reference line until you have a line that intersects the horizontal centerline at the middle mark.
Two switches (stacked vertically, with their levers traveling vertically) are 1.0" long. That fits in the cavity (perhaps dremeling a little more bulge away). So, I marked half the length of a switch (0.25") above/below the horizontal centerline. Those are the center of each switch. (Note: these top & bottom surfaces of the switch don't narrow like the sides.).
Stack the switches vertically on their sides (horizontal lever travel). I think that would be frustrating, switches moving in different directions than the "Al King tone" switch.
Do my original idea (side by side, vertical lever travel)—but 1/2" below the center line. That would have required "Al King tone" to be mounted 1/2" lower too, so it all looked consistent. I think it would also require all three bulges removed (ground flat against the cavity wall), and perhaps even deeper into the lower wall. (Then install new bulges juxtaposed: two on the top wall, one on the lower wall.).
That wouldn't be difficult to do. (Use some wooden dowel; file one side flat, into a semi-circle; epoxy this to the side of the cavity wall. Drill new holes for the cavity cover's screws.).
Depending on how low the switches could be, it might look really good. The might emphasize the contour of the body. I think the challenge would be the two tone switches side-by-side: How low they have to be for them to look proportionally spaced away from the faceplate & knob. If I did this mod again, I would spend more time considering that. (If the bulges were removed/juxtaposed, you could grind another 1/4" lower. It would just depend on what the switches would look like that low, or where they need to be in order to look right.).
While I wait for 22ga stranded wire. This seemed like a good place to break this mod into two parts. I'll post Part 2 when that's done. (That turned into a Part 3, as well.).
 For datasheet and dimensional drawings, see the individual product pages at LoveMySwitches. See Post #1 (this thread's intro), footnote 1 for more resources, and the possibility for black or gold finish.
Alternatively, this mod can be done with the 3-pos 4PDT (on-on-on) switch I used in the first wiring mod, "Al King tone". In that case, wire the lugs as if it's two of these switches side by side.
This time I used a scribe to make the indentation into the wood (while wearing a magnifying glass clipped to my glasses, going slow, making it deeper/larger with each confirmation). Then I used the center punch to enlarge it.
Once again, refer to the "Al King tone" mod for important info.
Notice where the bottom hole entered the cavity: on the edge of the bulge. The switch is 0.50" tall (top to bottom). Therefore, half the switch will live under the bulge. I.e., over 1/4" of the bulge's base has to be removed.
I should have done the dremel grinding before this step. That bulge could have deflected the bit to the side, causing an off-center/oblong hole.
In preparation for reaming, I ground the bulge's base away.
I was able to do about half the reaming until the tool began hitting the top of the bulge. I was worried that could cause the hole to be off-center.
I ground away some material from the top of the bulge (seen in the next step's photo). That let me almost finish reaming from the cavity side. I could've dremeled more away. Instead, I reamed more from the finish side (risking a [potentially] loose fit on the finish side due to the reamer's taper.). I went back and forth (reaming from cavity side, then finish side) trying to get to the point the switch would pass through. (Remember, don't force the switch into the hole. If it's hanging on the finish, you could damage the finish in the same way you tried to avoid with multiple drilling steps.).
Fortunately, my accident above (starting to drill in forward) didn't cause a problem. However, I believe I see some "hex" shape to that hole. I think I caused that by wiggling the reamer to remove it. I think the proper way is to continue twisting as you gently pull.
See the "Al King tone" mod for photos of the grinding bits I used, and warnings about using a dremel in your cavity.
I checked how far the switch threads protrude from the finish side. Like the "Al King tone" mod: it wasn't enough. Therefore, I removed the finish down to the wood. When I replace the layer of copper shield, that will make it just about right. (I can always use two layers if I overshot this.).
It was difficult to flatten the cavity floor. Each side drops off into the existing control holes (where the floor is thinner than the rest), making it difficult to know which level I wanted to be at. Also, the dremel's collar wanted to rub against the top of the bulge.
Mark and drill the new holes in your "jig." Same as before (tape your guitar's finish so the jig doesn't scratch).
This time I remembered to orient the switches with the "keyway" slot (in the threads) down. (I didn't think to do that with the "Al King tone" switch—until after I saw the slot showing in the photos.).
I'm still waiting for 22ga stranded wire. I'll post Part 3 (soldering, installation) when that's done.
I need to get wire too, whats your opinion on solid core wire, and is pre tinned copper better?
I contacted Dan Erlewine last year out of curiosity on how much it would cost to build a Lucy as that guitar is one of my all time favorites. Unfortunately I don't have the cash to have him build me one..
Love Albert King!! Very interesting build you are doing!!
Seymour Duncan Triple shoot pickup rings have switches.
Might be a Better solution than mini switches in most situations.
Very cool, following to see your finished special ii. I have one from a friend it was his first LP, maybe ill follow suit to get experience, id like to.
I'm glad you're inspired to do it. I hope you'll post your results, additional thoughts here. It's not hard. You just have to double/triple think everything. I try to imagine my guitar being a $2000 model, learning things from it that I'd be afraid to do to such. Thinking of it that way (being careful, patient) maximizes what I learn from the experience (getting the most from the mistakes I make). If I didn't do that, I'd plow into it like I'm hanging shelves on the wall, expecting it to turn out ok. I'm pretty sure that would be a frustrating experience. The other day I was thinking of this project like model-ship building. I've never done that. But, I imagine it's similar (going slow, being patient).
That was my goal when I started this stuff back in July/August. I was thinking there might be there might be other newbies (not that you are) who would welcome something different.
The next thing I'll experiment with is replacing pickup magnets. The factory pickups use ceramic magnets. Replacing those with Alinco could be a fun/inexpensive way to develop an ear for those things.
With your additional two switches: switchable modern/50s tone wiring? Or, switch different value capacitors? Or, a switchable tone-bleed?
If I had a 4-hole guitar, I'd do the "Jimmy Page" wiring. See this diagram which looks like it. (Archived, but you have to save the image and view it from your computer.).
That's everything I'm doing, plus "serial humbuckers" by itself (not sure if that's useful. Personally, I didn't like that sound). You won't get the choice of cut or parallel coils. But, they're both single-coil sounds. It's probably redundant to have both. (For my purpose of learning more, it might be useful to be able to switch between each, hear the differences better. It will probably be pointless pretty soon.).
I'm using 22ga. I liked solid because it makes the harness rigid, easier to handle. But, now it's getting tight, and I have to fiddle with things. I think stranded wire would be better. Solid weakens and breaks after a few flexes.
When I did the dual-concentric mod, I used stranded to connect the jack. I made a coil that tucks into the cavity; extends easily if the jack plate's removed. I'm going to use more stranded wire as I finish the coil-switches. I might replace a couple solid wires from the "Al King tone." It seems like the longer wires should be stranded. The shorter ones might be better solid, for a more rigid harness. The longer ones have more leverage, flex more.
[ EDIT: @Jewel the Sapphire , I forgot that you asked about pre-tinned wire. I haven't looked into that. All my wire wasn't. (The Gavitt 4-conductor pickup lead I used in that mod was). I thought tinned wire meant you don't have to tin it before soldering. But, there's not enough to create a solder joint (heating the two together without adding solder at the same time). When I tin the wire ends before making the joint, the amount of solder is considerably more than pre-tinned wire.
[EDIT again: @Jewel the Sapphire , actually I did get tinned wire. I was just tinning the pigtails and switch lugs, preparing to solder it all together. The 22ga stranded I was waiting for is tinned. And, the 22ga solid I bought previously is also tinned. (I wasn't paying attention.).
 22ga stranded, 8 colors, 5' long each, $8 USD shipped. eBay seller "longacdcwireandsupply."
 22ga solid, 5 colors, 25' long each. Philmore "hook up/lead wire kit" (22ga, solid) No. 12-2276. (I found this at Fry's Electronics. I don't recall what I paid.).
Wow, you went all in! I often use the 4pole dimarzio EP1111 and go with Petrucci wiring. Add a couple push pulls and you can do a lot without changing the look of the guitar at all. That said, looks pretty cool.
I hadn't heard of Petrucci wiring (nor the EP1111 switch). I googled about Petrucci wiring. It sounds interesting.
Also googled about the EP1111 switch. I saw it on Amazon for $30 USD. That switch looks almost identical to the Taiway #100-4P6-T200B1M1QE I used. The only difference: the Taiway cost $5. (I hope I don't sound too promotional, but I really like the people at LoveMySwitches. They got that switch in for me when I talked to them about it last September. I was expecting it to cost $30. That seems to be the going rate for 4PDT switches on guitar sites. Everything I saw was long-lever. That's why I contacted LoveMySwitches. They had other stubby-lever switches. I asked them to carry the 4PDT. (If I'd seen that EP1111, I would have paid $30 and never contacted LMS. Serendipity. Now you can save $15. ).
When I bought my used Special-II, I wanted to do mods like this, but didn't know what. Looking back on it, I would have been better off buying an LP-100 or Studio LT. Still near the "starter" range, but 4 knobs.
OTOH: if I bought a 4-knob guitar, I wouldn't have had a reason to do dual-concentric pots. That was an unusual mod. I strongly suggest it to Special-II owners (or anyone with 2 knobs). I noticed a very definite clarity or "spatial" change having the pickups on dedicated vol/tone controls. (Compared to converting the pickups to 4-conductor, and this switch mod, the dual-concentric was easy. A quick improvement in the sound.).
I wish I had a better ear for tone, more experience playing. I.e., I wish I could compare these mods to higher-end guitars. I wouldn't expect it to be equal. I understand there's matters of "tone wood," etc. But, I hear a big difference (probably due to the dual-concentric knobs, new capacitors, shielding).
I have heard that term/name, but didn't know what it was. I've been wanting switchable 50's- & modern-tone wiring for each pickup. If I used those rings I could do the coil switching there, and rewire the two toggles for 50s/modern.
The only thing is, it looks different. My primary motivation was to retain the traditional Special-II appearance. Drilling holes contradicts that. But, something about subtle toggles around the existing controls looks more traditional (to me) than the Triple-shot rings. (I'll eventually rationalize liking the rings... because I really want switchable 50s/modern.).
Something else I'm thinking about is a piezo/active bridge for a more acoustic sound. That probably requires using a router to enlarge the cavity (more than nibbling at the edges as I've done). I'd want a luthier to do that. Maybe it's possible to enlarge the Special-II's cavity into the LP Standard's cavity (while remaining 2-hole), use the Std's cover.
Duncan triple shot rings are just switches in the plastic pickup mounting ring.
They give you extra switches without making holes in your guitar.
If you’ve got to have the switches I get it. But it’s sometning to look at if you’re into endless switching options.
The taiway looks like a mini switch. The EP1111 is a drop in replacement for the LP toggle switch. You can get them for 20 bucks if you look around a bit. Just got another one last week. 4 pole switches can do so much. I have them in three guitars and they are all set up a little different. Basically two switches stuck together that you can cross wire so it's like flipping two switches at once. Amazing options available.
The taiway looks like a mini switch. The EP1111 is a drop in replacement for the LP toggle switch.
I just googled and saw a different product photo, and could see it was full size. (The Amazon photo, I couldn't tell.). I saw that kind of switch back in August when I was investigating what to do. I assume it would fit in the cavity. But, (no offence to anyone who has those switches installed), I didn't want my mod to stand out that much. Maybe a 4-knob's space/geometry would make that switch look like it fits. But, I couldn't picture that with the Special-II.
I was planning to do the "freeway" 6-position pickup selector, and try to get one or two things wired that way (not all of it, for sure). Then I saw the stubby toggles. That looked proportional. (Not to be promotional, but I was really thankful LoveMySwitches got the 4PDT for me. I don't think I would have done this mod if not. Or, it would have been a full-size lever on one side... two stubbies on the other. Not elegant.).
Just got another one last week. 4 pole switches can do so much. I have them in three guitars and they are all set up a little different. Basically two switches stuck together that you can cross wire so it's like flipping two switches at once. Amazing options available.
I agree. I would have never thought to expand "Al King tone" to 3 positions if I hadn't seen this this switch. I was googling for switches, hoping something would stand out to me. That switch was the only 4PDT I saw with a graphic illustration of how it works, and, a suggested use for it.
Once I saw that... It all fell into place. I wish more guitar-switch sellers would do that with their product pages. Give an example of how a switch is used. Then the visitor has a switch in search of a use (instead of a use in search of a switch). If I hadn't seen that page, my eyes would still glaze over at the thought of "4PDT, whatever that means."
THe freeway switches are a must for 3 pickup lp style guitars. I love them. But you’ve got to be extremely careful with your prep, solder heat and solder work.
There are lot of small connection points on those switches and the circuit board isn’t going to be as forgiving as a lug etc.
Great switches though. I very much like them. Totally worth the ca$h.
I contacted Dan Erlewine last year out of curiosity on how much it would cost to build a Lucy as that guitar is one of my all time favorites. Unfortunately I don't have the cash to have him build me one.
I wonder how much of that $9500 USD is because it's from the same tree (by the same luthier)? Have you considered making one yourself, or from a kit? (I just looked at Warmoth. They have a "V-K" kit available in walnut. That might be more fun, for $9000 less. There may be better options available. I don't know anything about making a guitar.).
I'm considering doing another Special-II to give as a gift (to have it on hand for such an opportunity). I'm watching for another $99 fixer-upper. (I got mine at Guitar Center, Mesa AZ. It needed a new jackplate. It was listed on their website, but they couldn't find it. I stood around for 30 minutes until they found it in the repair shop without a repair order. I suspect they were undecided whether it was worth fixing, and had been forgotten about. I felt like I "rescued" it. ).
After doing one of these, it's not much work. The first time it was challenging (and time consuming). Now, I think I could do one in a weekend (dual-contentric, 4-conductor and these tone switches). Maybe even a day if I tried. That would be a unique gift, mostly gifting the labor & know-how. It's fun to do too. Something unique compared to an off-the-shelf guitar.
Maybe you'd consider doing one of these? I'd love to know what an experienced player thinks of the resulting sound, before/after, what it might be comparable to (price range).
For me, I did these mods just to have something to do, learn more, document something for new players to do (when they typically want to do more than practice, but spending money on upgraded components is often discouraged as an unwise investment, "save your money, buy a better guitar."). I didn't have high hopes that I would create an exquisite guitar. Just something unique—more personal to me, while learning things I'd be afraid to on a $500 guitar. But, I do hear a noticeable improvement in the sound quality. Now I'm curious how it ranks with higher-end guitars (notwithstanding how being a Special-II will always limit it's value compared to a higher-end guitar). I don't have the experience/ear to know.
PS: I'm going to solder the switches and install today. I hope to post Part 3 today or tomorrow.