The 126 Vacuum Tube Theremin

Published August 23, 2002
Updated May 5, 2021


Contents

Legal Notice
Safety Notices
Acknowledgments
Introduction
Circuit Description
Schematics
Construction
Test Voltages
Photos
Parts Tables
Drawing Index




Update Notice

This version of the 126 Vacuum Tube Theremin consolidates previously-published editions.

The author is delighted that the 126 has enjoyed such unprecedented, long-term attention,
resulting in the construction of dozens of instruments since its original publication, 20 years ago.

Please feel free to contact me, should you need documentation from previous editions of this article.


Notice to Builders Outside the United States

 To assist builders outside the United States, items C5 and C24 (variable capacitors), L1, L2, L3 (coils),
and X1 (ceramic filter) are available as a kit from eBay as item 201981928615
.  
Builders within the United States should order these items from Harrison Instruments
.



Spot an error? (technical, grammatical, or speling)
Please send me an e-mail!




Legal Notice
(back to contents)


Legal Notice and Agreement


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Copyright Notification: ©2021 by Arthur Harrison. All rights reserved.

The CONTENT is the exclusive property of Arthur Harrison, hereafter referred to as the PROVIDER.

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THESE TERMS ARE PROTECTED BY INTERNATIONAL LAW. VIOLATORS WILL BE PROSECUTED.


.











Safety Notices
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Regarding the safety of your ears and hearing:

This circuit is recommended for users familiar with electronic theory and construction practices. It is recommended that suitable test equipment, including a frequency counter and oscilloscope, are available for making measurements.











Acknowledgments
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I express my sincere thanks to John Speulstra and Rick Hansen for their assistance in refreshing my knowledge of vacuum-tube techniques, and also to Steven Hasten for providing me with the incentive to pursue this design, and his construction efforts in verifying its performance. I also express my sincere thanks to Chris Fazi and Roger Kaul for assisting in the analysis of the volume control circuit design.











Introduction
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This is my second vacuum-tube theremin design, which is an expansion of its predecessor, the pitch-only 125 theremin. The 126 theremin has both pitch and volume features, as well as a tone control.

As in the 125 theremin, I have designed the 126 entirely with the popular 12AU7 vacuum tube. The pitch section consists of the classical two-oscillator heterodyne configuration, and the volume section employs a slope-detection method, with a ceramic filter. The ceramic filter provides the high selectivity required for the small frequency changes induced by hand capacitance, replacing the elaborate and costly inductor-type circuits usually used for this purpose. As with the 125 theremin, exceptional frequency stability for temperature variation is achieved, both in the pitch and volume sections.

The 126 theremin is designed with a plate-antenna configuration, capitalizing on the hand-to-plate coupling efficiency offered by this method. As with most of my dual-parameter theremins, two horizontal 8-inch by 5 1/2-inch rectangular antennas, extending from each side of the instrument, provide the gestural interface. The 126 theremin exhibits at least 5 octaves of pitch variation over a sensing distance of about 18 inches, and at least 45dB of dynamic volume range (closer-for-louder mode), over a sensing distance of about 10 inches, as illustrated in the following graphs:



126 Theremin Pitch Response



126 Theremin Volume Response



126 Theremin Sound Sample
©1972, Ron Miller, Michael Masser

126 Theremin Demonstration
©1958, Sammy Fain, Paul Webster









Circuit Description
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A selector switch in this design allows either "closer for louder" (CFL) or "closer for softer" (CFS) volume hand response, satisfying either player preference.

Vacuum tube V1A and its associated components form a Colpitts oscillator that includes hand capacitance, via antenna A1, as a frequency determinant. 455 kHz ceramic filter X1, driven by the oscillator via C7, performs the function of a frequency-slope detector. With the hand away from the antenna, the oscillator frequency is at resonance with X1, and the greatest amplitude sine wave is present at X1's output. As the hand approaches the antenna, the oscillator diminishes in frequency, resulting in a diminished amplitude at X1's output. Note that the center frequency of the ceramic filter is 455 kHz when used in a radio receiver with a specific intermediate-frequency transformer. However, in this application, the filter is less "loaded," and will exhibit a center frequency of about 458.5 kHz. The use of such a filter is particularly efficient in the design, since it permits a very low component count.

V1B amplifies the sine wave at X1's output, as well as providing impedance matching between X1 and the following circuit. The output of V1B is AC-coupled through C9 to V2A, a diode-configured triode used as a DC restorer, that establishes the bottom of the voltage waveform at about zero volts. As a result, the volume hand's proximity controls the positive-peak amplitude of the sine wave present at the grid and plate of V2B, a second diode-connected triode, which, in conjunction with C10 and R7, provides a DC voltage level corresponding to the peak value of the V2A sine wave. As the hand nears the antenna, the positive DC voltage at V2B's cathode diminishes.

This DC voltage level is applied to the grid of V3A via R8. Also applied to V3A's grid is the audio pitch waveform, via DC blocking capacitor C11. The resulting amplitude of the audio pitch waveform at V3A's cathode depends on the value of the DC voltage level from V2B, since V3A's conductance varies in accordance with that level.

Next, the signal is applied from V3A's cathode to V3B's cathode. V3B's grid has a switch-selected condition for either ground, or about +4.1 volts, via voltage divider R30 / R31. This provides a means to select V3B's operating point, allowing either volume response. Note that each section of V3, for most combinations of volume mode and hand distance, have their cathode potentials above the grids. This configuration provides a unconventional, but efficient, circuit solution. The following chart indicates V3 voltages. Measurements were made with B+ = 45 VDC, and a tone frequency of 440 Hz. AC voltages are peak-to-peak.


VOLUME MODE
HAND
DISTANCE
V3A PLATE
V3A GRID
V3A, B CATHODE
V3B GRID
V3B PLATE
CFL
12"
40 VDC
3.6 VDC &
580 mVAC
3.3 VDC &
500 mVAC
0 VDC
40 VDC &
2 mVAC
CFL
1"
41 DCV
380 mVDC &
580 mVAC
2.9 VDC &
340 mVAC
0 VDC
41 VDC &
500 mVAC
CFS
12"
39.5 DCV
3.6 VDC &
580 mVAC
5.3 VDC &
150 mVAC
4.1 VDC
34.5 VDC &
650 mVAC
CFS
1"
39.5 DCV
380 mVDC &
580 mVAC
5.2 VDC &
5 mVAC
4.1 VDC 34.5 VDC &
2 mVAC


The volume circuit exhibits at least 45 dB of dynamic range in both the CFLand CFS modes. The volume response curvature and dynamic range may vary with the particular tube used in the V3 position. Several tube brands, including "new-old stock" Ampere, Phillips, and RCA; and new Tesla brands were evaluated, all with sufficient performance.

The pitch circuit is shown on schematic page 2, below. V4 and associated components form a Colpitts oscillator that includes hand capacitance, via antenna A2, as a frequency determinant. Another oscillator, comprised of V6 and associated components, is the reference oscillator. The oscillators employ cathode-follower sections, V4A and V6A, to buffer their resonant networks from loading effects and to provide low impedance outputs. V5B is used as a mixer, with the pitch variable oscillator signal applied to its grid via capacitor C19, and the pitch reference oscillator signal applied to its cathode via resistor R21.

With tone-control potentiometer, RV1, in the extreme counterclockwise position, the reference oscillator output is coupled to the mixer via C28. Electrical coupling between the two oscillators occurs because the signal at V5B's cathode includes the signal present at it's grid. This signal, from the variable oscillator, is reflected back into the reference oscillator, via V6A's cathode. Under this condition, the maximum amount of oscillator coupling produces the greatest amount of harmonic content in the audio waveform.

With RV1 in the extreme clockwise position, the reference oscillator's output is isolated from the mixer via V5A. In this condition, the mixer's cathode signal has less influence on the reference oscillator, because it is attenuated by RV1's 50 kohm resistance. As a result, the harmonic content of the audio waveform is comparatively reduced.

The heterodyne of the two oscillator frequencies is present at V5B's plate. Two sections of low-pass filtering reduce the sum frequency product; C21 in conjunction with V5B's plate-circuit resistance, and R22 with C22.

The oscillator frequencies are described by the following equation:

For the volume oscillator, L is 1 mH, Ca is 330 pF, Cb is 100 pF, and Cc is the sum of C5, C6, and the A1 antenna capacitance. C5 is adjusted so that the volume oscillator's frequency is equal to X1's resonant frequency of 455 kHz with the hand away from antenna A1.

For the pitch oscillators, L is 1 mH, Ca is 1000 pF, Cb is 330 pF, and Cc is the A2 antenna capacitance (for the variable oscillator) or the value of the C24 pitch-zeroing capacitor (for the reference oscillator). Each of the pitch oscillator frequencies are typically 310 kHz.

As in any heterodyne theremin, an essential requirement is that the two pitch oscillators are very close in frequency, so that an audible tone can be produced. Optimally, the theremin should provide a "zero-beat" condition with C24 set to its mid-capacitance point, with the hand away from the pitch antenna. A low frequency audible output should result when the hand is brought within 12 to 24 inches of the pitch antenna, increasing in frequency as the hand becomes closer.

In most instances, component tolerances will cause the pitch oscillator frequencies to be too far apart to produce an audible tone, so a calibration procedure must be performed. To do this, measure the frequency of the pitch reference oscillator by connecting a counter to the cathode of V6A, and record that frequency. Then, move the counter to the cathode of V4A, which is the output of the variable oscillator. With variable capacitor C24 set to midpoint, and antenna A2 clear of objects, adjust the frequency of the pitch variable oscillator to match the recorded frequency, with one or more of the following methods:

Volume circuit calibration is performed by observing the RF voltage waveform at V1B's cathode. With C5 approximately centered and the hand away from A1, the waveform amplitude should peak, indicating volume oscillator resonance with X1. This corresponds to the center frequency of X1, which is 455 kHz. If this condition can not be obtained, then the volume oscillator's frequency may be adjusted with one or more of the following methods:

To eliminate the necessity for extensive trimming, the capacitors associated with the three oscillator frequency-determining networks (C2, C3, C6; C16, C17; C25, C26) should have ±5% or better tolerances. To ensure good frequency stability, these capacitors should be mica types, and the three oscillator coils, L1, L2, and L3 should be the J.W. Miller 4652 phenolic-core types specified. Capricious substitution of the coils may adversely affect or inhibit the theremin's operation.

Also, for frequency stability, C5 and C24 should be air-variable types. Too much capacitance change per degree of shaft rotation will degrade adjustment resolution. Therefore, a maximum value of 27 pF is recommended. Variable capacitors with a planetary reduction vernier will further enhance resolution. Such capacitors, with 3.85 turns of shaft rotation, are indicated in the schematic, and highly recommended.

The overall frequency of the theremin's operation may be changed with the substitution of frequency-determining components. However, the values indicated, providing approximately 310 kHz in the pitch circuit and 455 kHz in the volume circuit, were selected to prevent AM radio-band interference, while maintaining adequate hand-sensing distances.

The tone control's position has a slight effect on the pitch reference oscillator's frequency. Therefore, changing the tone will require a minor readjustment to pitch zero capacitor C24 for resetting the zero beat. However, this readjustment can be achieved easily.

The power supply is shown on schematic page 3, below. Voltage regulation is not employed in this circuit, since the oscillators exhibit excellent frequency stability with considerable supply variations. The total current drawn from the 50 volt supply is approximately 4 mA. Heater transformer T2 is rated to provide 10 volts RMS for a 1.2 A load. The six tubes use approximately 900 mA of heater current, so T1's actual loaded output is about 11.5 volts RMS, which is adequate for the 12.6 volt-rated 12AU7s or ECC82s. The theremin's parameters stabilize after a brief warm-up period of about three minutes. Thermal coefficients in the circuits have negligible contribution to long-term drift, with parameter readjustment only required due to shifts in the player's stance, or pitch readjustment when the tone setting is altered.

Some builders may wish to use alternative transformers to match their available mains voltage. If different transformers are used, measure the supply's output voltages while the theremin is connected, to ensure that the heater voltage is between 11.5 and 12.6 volts RMS AC, and that the B+ voltage is between 45 and 50 volts, DC.

To reduce the risk of injury, I designed this theremin with a maximum supply of approximately 50 volts, DC, which is considerably less than voltages used in many other vacuum-tube instruments. However, values substantially less than 50 volts can still be dangerous for conditions in which sufficient current is caused to flow through the body. Therefore, 330 pF ceramic capacitors C4 and C15 provide a safety function by preventing the presence of +50 volts on the antennas.

SAFETY NOTICE:




Schematics
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126 Theremin Scematic Page 1

126 Theremin Schematic Page 2

  126 Theremin Schematic Page 3

126 Theremin Transformer Terminal Identification











Construction
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The 126 theremin, illustrated below, is constructed on a 8" x 12" x 1/16"-thick aluminum Chassis Plate. The chassis is attached to a 11" x 17" x 1/2"-thick plywood Base with four threaded standoffs. The volume and pitch Antennas are 8" x 5 1/2" x 1/16"-thick aluminum plates that extend from the left and right edges of the base, respectively. The antennas are separated from the base with 1/2"-long threaded nylon standoffs to reduce their mutual capacitance, and connected to the circuit with 16 gauge solid bus wire. The wires are connected to the antennas with number-6 solder lugs, secured by one of the mounting screws at each antenna. The bottom of the base (not shown in the illustration) has an Atlas Sound type AD-11B threaded microphone stand adapter.

The 126 Theremin

The theremin's components, including two connectors and their brackets, are mounted on the bottom of the theremin mounting plate, with the tube envelopes and the control shafts for C5, C24, and RV1 on the top. The six 3/4" holes for the tube sockets and two 5/8" holes for the variable capacitors can be made with chassis punches (Greenlee types 730BB-3/4 and 730BB-5/8).

Refer to the Component Locations drawing. Screw-mounted Insulated Solder Turret Terminals provide junction points. Where required, component leads are insulated with 16 gauge Teflon® sleeving. Point-to point wiring is used, with 22 gauge, 19-strand Teflon®-insulated hookup wire, and 20 gauge solid tinned-copper bus wire, as required.

Regarding insulated hookup wire, the parts tables specify a variety of colors based upon wire function. Although color differentiation is good practice and recommended for electronic construction, the builder may economize by using only one color.

SAFETY NOTICE:

Wires are anchored to the theremin mounting plate, as required, with adhesive-backed mounts and nylon cable ties. Leave a little slack in the leads of the three coils so that they can be moved with relation to the plate. This technique permits small variations in capacitance that may be used to fine-adjust oscillator frequencies. Keep frequency-determining components C2, C3, C6, C16, C17, C25, C26, L1, L2, and L3 clear of other parts and wires. To prevent audible hum from the heater circuit, twist the heater wires tightly together and route them in a direct manner away from signal paths.

Ceramic filter X1 has relatively delicate, closely-spaced leads, nominally intended for printed-circuit board installation. To adapt X1, it is recommended that its center lead be soldered directly to the top of its respective turret terminal, and that short pieces of 20 gauge bus wire are soldered to the outside leads at right angles, and extended to the tops of their turret terminals. A version of the filter is also available with strain-relieved wire leads attached, as Harrison Instruments item number 99999-5915-126X1-1.

While assembling components onto the theremin mounting plate, temporarily attach four pair of long standoffs to the corner holes to protect the components from being damaged by the work surface:  Four 2 1/2" female-female standoffs on the top side of the plate, and four 2" male/female standoffs on the bottom. Each male/female standoff has a stud inserted through its hole to engage a standard spacer. Once all the parts have been assembled onto the plate, the temporary standoffs may be removed, and replaced with four 1 1/4"-long standoffs which are used to attach the plate to the wood base. Note: Apply a small amount of wax or oil to the male thread of the male/female standoffs before coupling them with the female standoffs, to prevent seizing.

Ground wiring may be "daisy-chained" in any convenient manner. Run a wire from each chain, as well as terminal 1 of power connector J1, to a single point on the metal chassis. The J2 output jack is a fully-insulated type, to prevent audible hum from ground loop currents. Its sleeve terminal connects to the single-point ground, as well. Variable capacitors C5 and C24 have their "rotor" terminals connected to their frames, and therefore become electrically grounded by their mechanical attachments to the mounting plate. Each variable capacitor has four solder lugs that are redundant "stator" terminals. On each capacitor, only one of these terminals is connected to V1A's and V6B's plate, respectively.

For safety, power supply components J3, F1, SW2, T1, T2, BR1, C30, C31, and R28 are fully enclosed in a 5" x 6" x 4" aluminum utility cabinet, separate from the main theremin assembly. J4 is an AC power inlet that mates with a 3-wire, grounded cord identical to the type used for most computers and test equipment. For construction simplicity, all the power supply parts are mounted to the inside surface of the utility cabinet's top panel, as illustrated in the Power Supply Lay-out drawing. Specific dimensions for the top panel are shown in the Power Supply Mounting Plate Hole Locations drawing. Note that the top panel is fabricated from 0.062"-thick aluminum, which replaces one of the two thinner, 0.040"-thick panels provided with the cabinet.

Adhesive-backed mounts and nylon cable ties are used to secure wires as required. The AC power inlet, fuse holder, switch, and transformer terminals are insulated with 1/8", 1/4, or 1/2"-diameter heat-shrink tubing, as required. Use the 1/2"-diameter tubing as an overall insulator for the rear of the fuse holder. Four self-adhesive feet are applied to the cabinet's bottom panel.

A four-wire extension cable with 9-pin "D" subminiature connectors connect the theremin assembly and power supply together. The length of the extension is optional, with about four feet being typical for extending from the floor to the top of a stand.

SAFETY NOTICES:  To prevent shock hazards from lethal mains voltage:

Test Voltages
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The following voltages are from the 126 theremin prototype, measured with a Tektronix type 485 oscilloscope, and a 10 Mohm, 10X-attenuation probe.
Due to variations in component tolerances, lay-out, and test conditions, user values may be different from those indicated

Unless otherwise noted:

  1. A1 and A2 are substituted with 10 pF mica capacitors, connected from C4 and C15 to ground, respectively.
  2. RV1 is adjusted fully clockwise.
  3. V4 or V6 are removed for some steps to simplify measurements.
Table NOTE:
  1. Adjust C5 for peak amplitude
  2. Frequency determined by C24 adjustment
  3. V6 removed
  4. V4 removed
  5. Value measured at the output jack with RV1 centered, and the pitch set with C24 at 440 Hz
  6. Probe loading has a significant effect on these measured values.


-

TEST POINT

NOTE

VALUE

-
B+ BR1+

-

+45 VDC with less than 40 mV P-P of both 60 Hz and RF
-
V1A plate V1-1 - 38 V P-P RF sine wave centered at +44.5 VDC
V1A grid V1-2 - 0 V (ground)
V1A cathode V1-3 - 10 V P-P RF sine wave centered at +2.7 VDC
V1B plate V1-6 1
4.0 V P-P RF sine wave centered at +24.3 VDC
V1B grid V1-7 1 1.6 V P-P RF sine wave centered at +2.9 VDC
V1B cathode V1-8 1 1.1 V P-P RF sine wave centered at +2.5 VDC
-
V2A plate V2-1 - 0 V (ground)
V2A grid V2-2 - 0 V (ground)
V2A cathode V2-3 1
4.3 V P-P RF sine wave with positive peak at +8 VDC, negative peak at -0.24 VDC
V2B plate V2-6 1 4.3 V P-P RF sine wave with positive peak at +8 VDC, negative peak at -0.24 VDC
V2B grid V2-7 1 4.3 V P-P RF sine wave with positive peak at +8 VDC, negative peak at -0.24 VDC
V2B cathode V2-8 1
+ 4.5 VDC
-
V3A plate V3-1

-

Refer to table in "Circuit Description" section
V3A grid V3-2 2 Refer to table in "Circuit Description" section
V3A cathode V3-3 - Refer to table in "Circuit Description" section
V3B plate V3-6

5

Refer to table in "Circuit Description" section
V3B grid V3-7

-

Refer to table in "Circuit Description" section
V3B cathode V3-8

-

Refer to table in "Circuit Description" section

V4A plate V4-1 3 +44.9 VDC with less than 40 mV P-P of both 60 Hz and RF
V4A grid V4-2 3, 6 6.5 VDC P-P RF sine wave centered at 0 V
V4A cathode V4-3 3 3.7 VDC P-P RF sine wave centered at +2.1 VDC
V4B plate V4-6 3 25 VDC P-P RF sine wave centered at +45.0 VDC
V4B grid V4-7 3 0 V (ground)
V4B cathode V4-8 3 3.6 V P-P RF sine wave centered at +3.3 VDC
-
V5A plate V5-1 - +44.9 VDC with less than 40 mV P-P of both 60 Hz and RF
V5A grid V5-2 - 3.6 V P-P RF sine wave centered at +2.2 V
V5A cathode V5-3 - 2.8 V P-P RF sine wave centered at +3.2 V
V5B plate V5-6 2
0.7 V P-P audio wave with 100 mV RF modulation.
V5B grid V5-7 - 3.5 V P-P RF sine wave centered at 0 V
V5B cathode V5-8 - 2.7 V P-P heterodyne wave centered at +2.5 V
-
V6A plate V6-1 4 +44.9 VDC with less than 40 mV P-P of both 60 Hz and RF
V6A grid V6-2
4, 6 6.7 V P-P RF sine wave centered at 0 V
V6A cathode V6-3 4 4.5 V P-P RF sine wave centered at +2.8 V
V6B plate V6-6 4 29 V P-P RF sine wave centered at +44.5 V
V6B grid V6-7 4 0 V (ground)
V6B cathode V6-8 4 4.5 V P-P RF sine wave centered at +4 V











Photos
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These are two photos of the 126 Theremin prototype, courtesy of Jack Hertz.








Johannes Graenzer of Bayreuth, Germany constructed this 126 Theremin with monopole antennas for his university project. He reports that the instrument worked "immediately... and sounds nearly as good as C. Rockmore's if you play it by making a little vibrato..."

Johannes Graenzer's Theremin








David Hunter of Toronto, Canada, built this 126 Theremin. The power supply is in the base, along with a speaker and amplifier.









Christopher Billey submitted this picture of his 126 Theremin. His version uses traditional antennas. It is his first vacuum tube theremin, and he reports that he is "very pleased with pitch range and sound quality."

Christopher Billey's Theremin






Brendan Pope, an 18 year-old student from North Carolina, built this version of the 126 Theremin for his school project. It is the first theremin he has ever owned or built. Brendon relates "Its sound is supreme to any other homemade theremin I've heard."

Brendan Pope's Theremin








Tomislav Ribicic of Croatia built this beautiful version of the 126 Theremin. The custom shellacked and waxed wood cabinet is topped by a stainless steel chassis plate. Traditional rod and loop antennas were used. Tomisalv reports that the theremin "sounds fabulous." He plans to install the instrument in the Caffe Jazz Tunel in Rijeka.

Tomislav Ribicic's Theremin







Yaroslav Sadovskiy of Moscow, Russia built this amazing version of the 126 Theremin. The six vacuum tubes are illuminated by LEDs, and the legends, laser cut into stainless steel plate, are likewise illuminated. Yaroslav reports good pitch sensing distance with the telescoping antenna, which also serves to fine-tune the theremin's zero in lieu of vernier capacitors. The wood sides add a "touch of vintageness," per Yaroslav, who also reports that the 126 "has the pure, classic theremin sound." The author is very pleased to have created this wonderful 126 in the city where Leon Theremin worked for a decade, at the Moscow Conservatory of Music.

Yaroslav Sadovskiy's Theremin, View 1

Yaroslav Sadovskiy's Theremin, View 2

Yaroslav Sadovskiy's Theremin, View 3

Yaroslav Sadovskiy's Theremin, View 4








Eric Reiswig from Canada built this excellent 126 Theremin with traditional loop and rod antennas fabricated from 3/8-inch diameter brass tubing. He incorporated the use of an IC reversing circuit to permit optional "closer-for-softer" volume response, and has expressed great satisfaction with the instrument's sound qualities.
Eric Reiswig's Theremin, View 1 Eric Reiswig's Theremin, View 2






Jeremy Merrill constructed this beautiful 126 Theremin in a wormy chestnut cabinet with a stainless steel chassis inset. He reports that the tone is excellent, and that his success has inspired him to build additional vacuum tube projects. The antennas are copper tubing, and the stand was adapted from a lamp.

Jeremy Merrill's Theremin, View 1 Jeremy Merrill's Theremin, View 3 Jeremy Merrill's Theremin, View 2









This wonderful rendition of the 126 is named The Spheremin by its creator, Francesco Zuddas of Monfalcone, Italy. Francesco relates that two of his friends, both violinists, played the instrument, and found it to be amazing. Francesco used DC switching power supplies of 12 and 48VDC to power his design, with excellent results.

Francesco Zuddas' Spheremin Front View Francesco Zuddas' Spheremin Rear View







James Means produced this fine 126 Theremin and reports that it sounds "great through his Fender Twin Reverb amp." The enclosure is reclaimed wood from furniture drawers.

James Means 126 Theremin Top View
James Means 126 Theremin Front View
James Means 126 Theremin Rear View







Guy Pasquet from the town of Joigny in the Burgandy region of France built this accurate version of the 126 Theremin. Guy is a veteran of electronics, born in 1927.

Guy Pasquet's Theremin, View 1
Guy Pasquet's Theremin, View 1









James Lafevre created this beautiful 126 theremin with spherical antennas. It utilizes the "Revision 3" volume circuit for either variation of volume detection.

James LeFevre's Theremin, View 1
James LeFevre 's Theremin, View 2







Marc Bareille, from France, built this superb 126 theremin with rod and loop antennas, and reports that it has great fideltiy, great stability, and range. Marc has a webpage that describes his construction.

Marc Bareille's Theremin







Bill Leake created this classical 126 theremin with particular attention to the article's exact recommendations, incorporating the revision 3 volume circuit.
He reports that the material cost (February, 2021) was about $700.
I have the pleasure of ongoing exchanges with Bill, who ran SPICE simulations for the instrument with a particular emphasis on the revision 3 volume circuit.

Bill Leake's Theremin







James Powell, a thereminist of many years, created this fascinating version of the 126 in a Sunbeam toaster enclosure.

James Powell's 126 Theremin Exterior
James Powell's 126 Theremin Interior









Parts Tables
(back to contents)

Table 1 Theremin Assembly (schematic-designated items)
Table 2 Power Supply Assembly (schematic-designated items)
Table 3 Theremin Assembly (hardware items)
Table 4 Power Supply Assembly (hardware items)
Table 5 Base Assembly
Table 6 Cable Assembly
Table 7 Fixture Items



Parts Table 1 ^
Theremin Assembly (schematic-designated items)
LINE ITEM DESCRIPTION VALUE MANUFACTURER

MANUFACTURER PART
NUMBER

SUPPLIER SUPPLIER
STOCK
NUMBER
QTY
101 A1,A2 ANTENNA
(PER DRAWING)

(SEE NOTE 1,
ABOVE)
. . . MCMASTER-CARR 89015K37 1
102 C1, C14, C20, C23, C32
ELECTROLYTIC
CAPACITOR
10 uF ±20%,
100 V,
105 °C,
RADIAL,
6.3 mm D x 11 mm L
NICHICON UPW2A100MED MOUSER
ELECTRONICS
647-UPW2A100MED 5
103 C2, C17, C26 MICA
CAPACITOR
330 pF ±5%,
500 V
CORNELL
DUBILIER
CD19FD331JO3 MOUSER
ELECTRONICS
5982-19-500V330 3
104 C3 MICA
CAPACITOR
100 pF ±5%,
500 V
CORNELL
DUBILIER
CD15FD101JO3 MOUSER
ELECTRONICS
5982-15-500V100 1
105 C4, C15 CERAMIC
CAPACITOR
330 pF ±10%,
X7R,
200 V,
RADIAL
AVX CK05BX331K MOUSER
ELECTRONICS
581-CK05BX331K 2
106 C5, C24 VARIABLE
CAPACITOR
6.2-27 pF,
8:1
VERNIER
HARRISON
INSTRUMENTS
99999-
5910-7-27R0
HARRISON
INSTRUMENTS
99999-5910-7-27R0
2
107 C6 MICA
CAPACITOR
10 pF ±5%,
500 V
CORNELL
DUBILIER
CD10CD100DO3 MOUSER
ELECTRONICS
5982-10-500V10 1
108 C7, C8, C21, C22 CERAMIC
CAPACITOR
1000 pF ±10%,
X7R,
200 V,
RADIAL
AVX CK05BX102K MOUSER
ELECTRONICS
581-CK05BX102K 4
109 C9, C10, C11, C13,
C18, C19, C27,
C28, C29
METALIZED
POLYESTER
CAPACITOR
0.01 uF ±5%,
400 V,
AXIAL
VISHAY/
ROEDERSTEIN
MKT1813310404 MOUSER
ELECTRONICS
75-MKT1813310404 9
110
C12
ELECTROLYTIC
CAPACITOR
100 uF ±20%,
100 V,
85 °C,
RADIAL,
10 mm D x 20 mm L
NICHICON 647-UVR2A101MPD
MOUSER
ELECTRONICS
647-UVR2A101MPD 1
111 C16, C25 MICA
CAPACITOR
1000 pF ±5%,
500 V
CORNELL
DUBILIER
CD19FD102JO3 MOUSER
ELECTRONICS
5982-19-500V1000 2
112† J1 CONNECTOR 9 POSITION,
MALE CONTACTS,
D-SUBMINIATURE
CINCH DEH-9P MOUSER
ELECTRONICS
538-DEH-9P 1
113 J2 PHONE JACK, WITH HARDWARE 1/4",
INSULATED,
MONOPHONIC
SWITCHCRAFT N111X MOUSER
ELECTRONICS
502-N-111X 1
114 L1, L2,
L3
INDUCTOR,
THREE-SECTION,
UNIVERSAL
"PIE" WOUND
1 mH ±5%,
19 ohm
Q = 59 @ 0.25MHz,
SRF = 3.7MHz MINIMUM

J.W. MILLER 4652 HARRISON
INSTRUMENTS
96804-4652 3
115 R1, R13
R18, R23
RESISTOR 5600 ohm ±5%,
1/2W,
CARBON FILM
XICON 293-5.6K-RC MOUSER
ELECTRONICS
293-5.6K-RC 4
116 R2 RESISTOR 33.2 kohm ±1%,
±100PPM/°C
1/4W,
METAL FILM
VISHAY / DALE RN60D3322FB14 MOUSER
ELECTRONICS
71-RN60D-F-33.2K 1
117 R3, R30
RESISTOR 390 kohm ±5%,
1/2W,
CARBON FILM
XICON 293-390K-RC MOUSER
ELECTRONICS
293-390K-RC 2
118 R4, R5, R7,
R8, R12, R15
R17, R25
RESISTOR 1  Mohm ±5%,
1/2W,
CARBON FILM
XICON 293-1M-RC MOUSER
ELECTRONICS
293-1M-RC 8
119 R6 RESISTOR 2000 ohm ±5%,
1/2W,
CARBON FILM
XICON 293-2K-RC MOUSER
ELECTRONICS
293-2K-RC 1
120 R9, R10, R11, R32
RESISTOR 10 kohm ±5%,
1/2W,
CARBON FILM
XICON 293-10K-RC MOUSER
ELECTRONICS
293-10K-RC 4
121 R14, R24 RESISTOR 39.2 kohm ±1%,
±100PPM/°C
1/4W,
METAL FILM
VISHAY / DALE RN60D3922FB14 MOUSER
ELECTRONICS
71-RN60D-F-39.2K 2
122 R16, R26, R27 RESISTOR 3900 ohm ±5%,
1/2W,
CARBON FILM
XICON 293-3.9K-RC MOUSER
ELECTRONICS
293-3.9K-RC 3
123 R19 RESISTOR 100 kohm ±5%,
1/2W,
CARBON FILM
XICON 293-100K-RC MOUSER
ELECTRONICS
293-100K-RC 1
124 R20, R21, R22, R31
RESISTOR 39 kohm ±5%,
1/2W,
CARBON FILM
XICON 293-39K-RC MOUSER
ELECTRONICS
293-39K-RC 4
125 R29 RESISTOR 18 kohm ±5%,
1/2W,
CARBON FILM
XICON 293-18K-RC MOUSER
ELECTRONICS
293-18K-RC 1
126 RV1 POTENTIOMETER,
WITH HARDWARE
50 kohm ±20%,
0.25 WATT,
CARBON COMPOSITION,
AUDIO
TAPER
,
WITH
MOUNTING
NUT AND
FLAT WASHER
ALPHA RV24AF-10-
15R1-A50K-3
MOUSER
ELECTRONICS
31VJ405-F3 1
127 SW1
SWITCH, TOGGLE,
WITH
HARDWARE
6 A,
250 V,
SPDT
NKK
M2012SS1W01 MOUSER
ELECTRONICS
633-M201201 1
128 V1, V2, V3
V4, V5, V6
VACUUM TUBE,
DUAL TRIODE
. TESLA ECC82 ANTIQUE
ELECTRONICS
SUPPLY
T-12AU7-JJ 6
129 X1 CERAMIC FILTER

(SEE NOTES 4 AND 5, ABOVE)
UNLOADED fo = 462 kHz ±2 kHz,
3dB BDW = 10 kHz ±3 kHz,
RIPPLE = 0 dB,
MAX. INSERTION LOSS = 5 dB
Zin = 3 kohm
Zout = 3 kohm
MURATA
SIGNAL
CONDITIONING
PRODUCTS
SFULA455KU2A-B0 HARRISON
INSTRUMENTS
99999-5915-126X1 1


Parts Table 2 ^
Power Supply Assembly (schematic-designated items)
LINE

VALUE MANUFACTURER MANUFACTURER PART NUMBER SUPPLIER SUPPLIER STOCK NUMBER QTY
201 BR1 RECTIFIER BRIDGE 6 A,
200 V
RECTRON BR62 MOUSER
ELECTRONICS
583-BR62 1
202 C30, C31 ELECTROLYTIC CAPACITOR 330 uF ±20%,
100 V,
85 °C,
AXIAL,
13mm D x 31.5mm L
NICHICON TVX2A331MCD MOUSER
ELECTRONICS
647-TVX2A331MCD 2
203 F1 CARTRIDGE FUSE 1/8 A,
250 V,
SLOW-ACTING,
0.25" D x 1.25" L
LITTELFUSE 576-0313.125MXP MOUSER
ELECTRONICS
576-0313.125MXP 1
204† J3 CONNECTOR 9 POSITION,
FEMALE CONTACTS,
D-SUBMIN-
IATURE
CINCH DEH-9S MOUSER
ELECTRONICS
538-DEH-9S 1
205 J4 AC POWER INLET 250 VAC,
15 A,
CLASS 1
DGS PRO-AUDIO 161-0707-1-E MOUSER
ELECTRONICS
161-0707-1-E 1
206 R28 RESISTOR 100 ohm ±5%,
1/2 W,
CARBON FILM
XICON 293-100-RC MOUSER
ELECTRONICS
293-100-RC 1
207 SW2
SWITCH, TOGGLE,
WITH
HARDWARE
6 A,
250 V,
SPDT
NKK M2012SS1W01 MOUSER
ELECTRONICS
633-M201201 1
208 T1 TRANSFORMER

(SEE NOTE 3,
ABOVE)

PRIMARY:
120 V, 60Hz
SECONDARY:
28 V, 85mA
SIGNAL TRANSFORMER COMPANY 241-3-28 SIGNAL
TRANSFORMER
COMPANY
241-3-28 1
209 T2 TRANSFORMER

(SEE NOTE 3,
ABOVE)

PRIMARY:
120 V, 60 Hz
SECONDARY:
10 V, 1.2 A
SIGNAL TRANSFORMER COMPANY 241-5-10 SIGNAL
TRANSFORMER
COMPANY
241-5-10 1


Parts Table 3 ^
Theremin Assembly (hardware items)
LINE ITEM DESCRIPTION MANUFACTURER

MANUFACTURER PART
NUMBER

SUPPLIER SUPPLIER
STOCK
NUMBER
QTY
301 THEREMIN MOUNTING PLATE (PER DRAWING) . . MCMASTER-CARR 89015K37 1
302 STANDOFF, THEREMIN MOUNTING PLATE 6-32 x
1.25" L,
HEXAGONAL,
ALUMINUM
KEYSTONE 1818 MOUSER
ELECTRONICS
534-1818 4
303 MACHINE SCREW, STANDOFF, THEREMIN MOUNTING PLATE PAN HEAD,
SLOTTED,
6-32 x 0.375",

STAINLESS STEEL
. . MCMASTER-CARR 91792A146
(PACKAGE OF 100)
4
304† FLAT WASHER, STANDOFF, THEREMIN MOUNTING PLATE #6,
0.312" O.D.,

STAINLESS STEEL
. . MCMASTER-CARR 98019A314
(PACKAGE OF 500)
4
305† LOCK WASHER, STANDOFF, THEREMIN MOUNTING PLATE #6 SPLIT-RING,
0.250" O.D.,
STAINLESS STEEL
. . MCMASTER-CARR 92146A540
(PACKAGE OF 100)
4
306 BRACKET, OUTPUT JACK (PER DRAWING) . . MCMASTER-CARR 8199K13 1
307† MACHINE SCREW, BRACKET, OUTPUT JACK PAN HEAD,
SLOTTED,
4-40 x 0.312",
STAINLESS STEEL
. . MCMASTER-CARR 91792A107
(PACKAGE OF 100)
2
308† FLAT WASHER, BRACKET, OUTPUT JACK #4,
0.250" O.D.,
STAINLESS STEEL
. . MCMASTER-CARR 98019A309
(PACKAGE OF 500)
2
309† LOCK WASHER, BRACKET, OUTPUT JACK #4 SPLIT-RING,
0.209 O.D.,
STAINLESS STEEL
. . MCMASTER-CARR 92146A530
(PACKAGE OF 100)
2
310† NUT, BRACKET, OUTPUT JACK HEX,
4-40 x 0.250",
STAINLESS STEEL
. . MCMASTER-CARR 91841A005
(PACKAGE OF 100)
2
311 BRACKET,
POWER CONNECTOR
(MODIFIED PER
DRAWING
)
KEYSTONE 621 MOUSER
ELECTRONICS
534-621 2
312† MACHINE SCREW, BRACKET, POWER CONNECTOR PAN HEAD,
SLOTTED,
4-40 x 0.250",
STAINLESS STEEL
. . MCMASTER-CARR 91792A106
(PACKAGE OF 100)
2
313† FLAT WASHER, BRACKET, POWER CONNECTOR #4,
0.250" O.D.,
STAINLESS STEEL
. . MCMASTER-CARR 98019A309
(PACKAGE OF 500)
2
314† LOCK WASHER, BRACKET, POWER CONNECTOR #4 SPLIT-RING,
0.209 O.D.,
STAINLESS STEEL
. . MCMASTER-CARR 92146A530
(PACKAGE OF 100)
2
315† JACK SCREW WITH HARDWARE, POWER CONNECTOR 4-40,
0.250" L
STUD
KEYSTONE . MOUSER
ELECTRONICS
534-7229
2
316† TERMINAL INSULATED,
SOLDER TURRET,
4-40 INTERNAL THREAD
WEARNES
CAMBION
572-4814-01-05-16 BISCO
INDUSTRIES
572-4814-01-05-16 49
317† MACHINE SCREW, TERMINAL PAN HEAD,
SLOTTED,
4-40 x 0.250",
STAINLESS STEEL
. . MCMASTER-CARR 91792A106
(PACKAGE OF 100)
49
318† FLAT WASHER, TERMINAL #4,
0.250" O.D.,
STAINLESS STEEL
. . MCMASTER-CARR 98019A309
(PACKAGE OF 500)
49
319† LOCK WASHER, TERMINAL #4 SPLIT-RING,
0.209 O.D.,
STAINLESS STEEL
. . MCMASTER-CARR 92146A530
(PACKAGE OF 100)
49
320 SOCKET, TUBE 9-PIN,
MINIATURE,
WITH SHIELD RETAINER,
0.750" DIAMETER MTG HOLE,
TOP-MOUNTED
BELTON VT-9-ST-C TUBE DEPOT SK-B-VT9-ST-C 6
321† MACHINE SCREW, TUBE SOCKET PAN HEAD,
SLOTTED,
4-40 x 0.312",
STAINLESS STEEL
. . MCMASTER-CARR 91792A107
(PACKAGE OF 100)
12
322† FLAT WASHER, TUBE SOCKET #4,
0.250" O.D.,
STAINLESS STEEL
. . MCMASTER-CARR 98019A309
(PACKAGE OF 500)
12
323† LOCK WASHER, TUBE SOCKET #4 SPLIT-RING,
0.209 O.D.,
STAINLESS STEEL
. . MCMASTER-CARR 92146A530
(PACKAGE OF 100)
12
324† NUT, TUBE SOCKET HEX,
4-40 x 0.250",
STAINLESS STEEL
. . MCMASTER-CARR 91841A005
(PACKAGE OF 100)
12
325 MACHINE SCREW, VARIABLE CAPACITOR PAN HEAD,
SLOTTED,
6-32 x 0.250",
STAINLESS STEEL
. . MCMASTER-CARR 91792A144
(PACKAGE OF 100)
4
326† FLAT WASHER, VARIABLE CAPACITOR #6,
0.312" O.D.,
STAINLESS STEEL
. . MCMASTER-CARR 98019A314
(PACKAGE OF 500)
4
327† LOCK WASHER, VARIABLE CAPACITOR #6 SPLIT-RING,
0.250" O.D.,
STAINLESS STEEL
. . MCMASTER-CARR 92146A540
(PACKAGE OF 100)
4
328 KNOB, WITH SET SCREW 25/32" D,
15/32" H,
FOR 0.250" SHAFT,
PHENOLIC,
BLACK
DAVIES 1100 MOUSER
ELECTRONICS
5164-1100 3
329† LUG, GROUNDING #4,
INTERNAL TOOTH,
0.63" x 0.31"
KEYSTONE 908 MOUSER
ELECTRONICS
534-908 1
330† MACHINE SCREW, LUG, GROUNDING PAN HEAD,
SLOTTED,
4-40 x 0.250",
STAINLESS STEEL
. . MCMASTER-CARR 91792A106
(PACKAGE OF 100)
1
331† FLAT WASHER, LUG, GROUNDING #4,
0.250" O.D.,
STAINLESS STEEL
. . MCMASTER-CARR 98019A309
(PACKAGE OF 500)
1
332† NUT, LUG, GROUNDING HEX,
4-40 x 0.250",
STAINLESS STEEL
. . MCMASTER-CARR 91841A005
(PACKAGE OF 100)
1
333† WIRE, HOOKUP, DC RETURN BLACK,
22 GAUGE,
TEFLON® INSULATED,
100' ROLL
WEICO WIRE M16878/4BFE-0 WEICO WIRE & CABLE 2122/19-BLACK
(ROLL OF 100')
A/R
334† WIRE, HOOKUP, B+ RED,
22 GAUGE,
TEFLON® INSULATED,
100' ROLL
WEICO WIRE M16878/4BFE-2 WEICO WIRE & CABLE 2122/19-RED
(ROLL OF 100')
A/R
335 WIRE, HOOKUP, SIGNAL BLUE,
22 GAUGE,
TEFLON® INSULATED,
100' ROLL
WEICO WIRE M16878/4BFE-6 WEICO WIRE & CABLE 2122/19-BLUE
(ROLL OF 100')
A/R
336† WIRE, HOOKUP, HEATER GRAY,
22 GAUGE,
TEFLON® INSULATED,
100' ROLL
WEICO WIRE M16878/4BFE-8 WEICO WIRE & CABLE 2122/19-GRAY
(ROLL OF 100')
A/R
337† WIRE, BUS 20 GAUGE,
TINNED COPPER,
100' ROLL
WEICO WIRE 9020 WEICO WIRE & CABLE 9020
(ROLL OF 100')
A/R
338 WIRE, BUS, ANTENNA LEAD-IN 16 GAUGE,
TINNED COPPER,
100' ROLL
WEICO WIRE 9016 WEICO WIRE & CABLE 9016
(ROLL OF 100')
A/R
339 SLEEVING,
INSULATION
16 GAUGE,
TEFLON®,
100' ROLL
WEICO WIRE TS-16 WEICO WIRE & CABLE TS-16
(ROLL OF 100')
A/R
340 LUG, ANTENNA #6,
INTERNAL TOOTH,
0.63" x 0.31"
KEYSTONE 914 MOUSER
ELECTRONICS
534-914 2
341 WIRE TIE NYLON,
3.9" L
PANDUIT PLT1M-C MOUSER
ELECTRONICS
644-PLT1M-C A/R
342 ANCHOR, WIRE TIE NYLON,
1/2" SQ
PANDUIT ABM1M-A-M MOUSER
ELECTRONICS
644-ABM1M-A-M A/R


Parts Table 4 ^
Power Supply Assembly (hardware items)
LINE ITEM DESCRIPTION MANUFACTURER

MANUFACTURER PART
NUMBER

SUPPLIER SUPPLIER
STOCK
NUMBER
QTY
401 POWER SUPPLY
MOUNTING PLATE
(PER DRAWING) . . MCMASTER-CARR 89015K37 1
402 UTILITY CABINET,
POWER SUPPLY,
WITH HARDWARE
2-PANEL,
ALUMINUM,
5" x 6" x 4"
BUD INDUSTRIES AU-1029 MOUSER
ELECTRONICS
563-AU-1029NF 1
403 FOOT, UTILITY CABINET 0.81" SQ x 0.3" H,
SELF ADHESIVE, GRAY
3M SJ-5023GY MOUSER
ELECTRONICS
517-SJ-5023GY 4
404 MACHINE SCREW,
AC POWER
INLET MOUNTING
FLAT HEAD,
SLOTTED,
4-40 x 0.375",
STAINLESS STEEL
. . MCMASTER-CARR 91781A108
FLAT HEAD
(PACKAGE OF 100)
2
405† NUT,
AC POWER
INLET MOUNTING
HEX,
4-40 X 0.250",
STAINLESS STEEL
. . MCMASTER-CARR 91841A005
(PACKAGE OF 100)
2
406† FLAT WASHER,
AC POWER
INLET MOUNTING
#4,
0.250" 0.D.,
STAINLESS STEEL
. . MCMASTER-CARR 98019A309
(PACKAGE OF 500)
2
407† LOCK WASHER,
AC POWER
INLET MOUNTING
#4 SPLIT-RING,
0.209" O.D.,
STAINLESS STEEL
. . MCMASTER-CARR 92146A530
(PACKAGE OF 100)
2
408† LUG, GROUND #4,
INTERNAL TOOTH,
0.63" x 0.31"
KEYSTONE 908 MOUSER
ELECTRONICS
534-908 1
409† MACHINE SCREW, LUG, GROUND PAN HEAD,
SLOTTED,
4-40 x 0.250",
STAINLESS STEEL
. 0.25" D x 1.25" L . MCMASTER-CARR 91792A106
(PACKAGE OF 100)
1
410† FLAT WASHER, LUG, GROUND #4,
0.250" O.D.,
STAINLESS STEEL
. . MCMASTER-CARR 98019A309
(PACKAGE OF 500)
1
411† NUT, LUG, GROUND HEX,
4-40 x 0.250",
STAINLESS STEEL
. . MCMASTER-CARR 91841A005
(PACKAGE OF 100)
1
412† MACHINE SCREW, TRANSFORMER PAN HEAD,
SLOTTED,
6-32 x 0.437",
STAINLESS STEEL
. . MCMASTER-CARR 91792A147
(PACKAGE OF 100)
4
413† FLAT WASHER, TRANSFORMER #6,
0.312 O.D., STAINLESS STEEL
. . MCMASTER-CARR 98019A314
(PACKAGE OF 100)
4
414† LOCK WASHER, TRANSFORMER #6 SPLIT-RING, 0.250" O.D., STAINLESS STEEL . . MCMASTER-CARR 92146A540
(PACKAGE OF 100)
4
415† NUT, TRANSFORMER HEX,
6-32 x 0.250", SMALL PATTERN, STAINLESS STEEL
. . MCMASTER-CARR 90730A007
(PACKAGE OF 100)
4
416† MACHINE SCREW,
BRIDGE RECTIFIER
PAN HEAD,
SLOTTED,
6-32 x 0.437", STAINLESS STEEL
. . MCMASTER-CARR 91792A147
(PACKAGE OF 100)
1
417† FLAT WASHER,
BRIDGE RECTIFIER
#6,
0.312" 0.D.,
STAINLESS STEEL
. . MCMASTER-CARR 98019A314
(PACKAGE OF 500)
1
418† LOCK WASHER,
BRIDGE RECTIFIER
#6 SPLIT-RING,
0.250" O.D.,
STAINLESS STEEL
. . MCMASTER-CARR 92146A540
(PACKAGE OF 100)
1
419† NUT,
BRIDGE RECTIFIER
HEX,
6-32 x 0.250",
SMALL PATTERN,
STAINLESS STEEL
. . MCMASTER-CARR 90730A007
(PACKAGE OF 100)
1
420† TERMINAL INSULATED,
SOLDER TURRET,
4-40 INTERNAL THREAD
WEARNES
CAMBION
572-4814-
01-05-16
BISCO
INDUSTRIES
572-4814-01-05-16 4
421† MACHINE SCREW,
TERMINAL
PAN HEAD,
SLOTTED,
4-40 x 0.250",
STAINLESS STEEL
. . MCMASTER-CARR 91792A106
(PACKAGE OF 100)
4
422† FLAT WASHER,
TERMINAL
#4,
0.250" O.D.,
STAINLESS STEEL
. . MCMASTER-CARR 98019A309
(PACKAGE OF 500)
4
423† LOCK WASHER,
TERMINAL
#4 SPLIT-RING,
0.209" O.D.,
STAINLESS STEEL
. . MCMASTER-CARR 92146A530
(PACKAGE OF 100)
4
424† JACK SCREW WITH HARDWARE, POWER CONNECTOR 4-40,
0.250" L
KEYSTONE 7229 MOUSER
ELECTRONICS
534-7229 2
425† WIRE, HOOKUP, TRANSFORMER PRIMARY LINE BLACK,
22 GAUGE,
TEFLON®
INSULATED,
100' ROLL
WEICO WIRE M16878/4BFE-0 WEICO WIRE & CABLE 2122/19-BLACK
(ROLL OF 100')
A/R
426† WIRE, HOOKUP, B+ RED,
22 GAUGE,
TEFLON®
INSULATED,
100' ROLL
WEICO WIRE M16878/4BFE-2 WEICO WIRE & CABLE
2122/19-RED
(ROLL OF 100')
A/R
427 WIRE, HOOKUP,
B+ TRANSFORMER
SECONDARY
YELLOW,
22 GAUGE,
TEFLON®
INSULATED,
100' ROLL
WEICO WIRE M16878/4BFE-4 WEICO WIRE & CABLE
2122/19-YELLOW
(ROLL OF 100')
A/R
428 WIRE, HOOKUP,
SAFETY GROUND
GREEN,
22 GAUGE,
TEFLON®
INSULATED,
100' ROLL
WEICO WIRE M16878/4BFE-5 WEICO WIRE & CABLE
2122/19-GREEN
(ROLL OF 100')
A/R
429† WIRE, HOOKUP,
HEATER
TRANSFORMER
SECONDARY
GRAY,
22 GAUGE,
TEFLON®
INSULATED,
100' ROLL
WEICO WIRE M16878/4BFE-8 WEICO WIRE & CABLE
2122/19-GRAY
(ROLL OF 100')
A/R
430 WIRE, HOOKUP,
TRANSFORMER
PRIMARY NEUTRAL
WHITE,
22 GAUGE,
TEFLON®
INSULATED,
100' ROLL
WEICO WIRE M16878/4BFE-9 WEICO WIRE & CABLE
2122/19-WHITE
(ROLL OF 100')
A/R
431† WIRE, BUS 20 GAUGE,
TINNED COPPER,
100' ROLL
WEICO WIRE 297 SV005 WEICO WIRE & CABLE 602-297-100 A/R
432 TUBING,
HEAT-SHRINKABLE
POLYOLEFIN,
BLACK,
0.125"O.D.,
48"
3M FP301 1/8 BLACK MOUSER
ELECTRONICS
5174-1181 A/R
433 TUBING,
HEAT-SHRINKABLE
POLYOLEFIN,
BLACK,
0.250"O.D.,
48"
3M FP301 1/4 BLACK MOUSER
ELECTRONICS
5174-1141 A/R
434 TUBING,
HEAT-SHRINKABLE
POLYOLEFIN,
BLACK,
0.500"O.D.,
48"
3M FP301 1/2 BLACK MOUSER
ELECTRONICS
5174-1121 A/R
435
HOLDER, FUSE,
FOR 0.25" D x 1.25" L FUSE
HKP-HH-R BUSSMANN
HKP-HH-R MOUSER
ELECTRONICS
504-HKP-HH-R
1


Parts Table 5 ^
Base Assembly
LINE ITEM DESCRIPTION MANUFACTURER

MANUFACTURER PART
NUMBER

SUPPLIER SUPPLIER
STOCK
NUMBER
QTY
501 BASE (SEE NOTE 2,
ABOVE)
. . . . 1
502 STANDOFF,
ANTENNA
6-32 x
0.500" L,
HEXAGONAL,
NYLON
KEYSTONE 1903C MOUSER
ELECTRONICS
534-1903C 8
503† MACHINE SCREW,
ANTENNA
PAN HEAD,
SLOTTED,
6-32 x 0.312",
STAINLESS STEEL
. . MCMASTER-CARR 91792A145
(PACKAGE 0F 100)
8
504† FLAT WASHER,
ANTENNA
#6,
0.312" O.D.,
STAINLESS STEEL
. . MCMASTER-CARR 98019A314
(PACKAGE OF 500)
8
505† LOCK WASHER,
ANTENNA
#6 SPLIT-RING,
0.250" O.D.,
STAINLESS STEEL
. . MCMASTER-CARR 92146A540
(PACKAGE OF 100)
8
506 MACHINE SCREW,
BASE
FLAT HEAD,
SLOTTED,
6-32 x 0.625",
STAINLESS STEEL
. . MCMASTER-CARR 91781A150
FLAT HEAD
(PACKAGE OF
100)
12
507 ADAPTER,
MICROPHONE
STAND
1.75" O.D.,
0.71" H,
5/8-27 INTERNAL THREAD
ATLAS SOUND AD-11B HARRISON
INSTRUMENTS
99999-AD-11B 1
508 THREAD-FORMING SCREW,
ADAPTER
PAN HEAD,
TYPE A,
PHILLIPS,
#6 X 1/2"
,
STAINLESS STEEL
. . MCMASTER-CARR 92470A148
(PACKAGE OF 100)
3


Parts Table 6 ^
Cable Assembly
LINE ITEM DESCRIPTION VALUE MANUFACTURER

MANUFACTURER PART
NUMBER

SUPPLIER SUPPLIER
STOCK
NUMBER
QTY
601 . CABLE,
4-CONDUCTOR
4 22-GAUGE,
7 x 30
STRAND TINNED
COPPER
CONDUCTORS,
PVC INSULATED,
PVC JACKET,
0.185" O.D.
BELDEN 8444 MOUSER
ELECTRONICS
566-8444-100
(ROLL OF 100')
A/R
602† P1 CONNECTOR,
4-CONDUCTOR
CABLE
9 POSITION,
MALE CONTACTS,
D-SUBMINIATURE
CINCH DEH-9P MOUSER
ELECTRONICS
538-DEH-9P 1
603† P2 CONNECTOR,
4-CONDUCTOR
CABLE
9 POSITION,
FEMALE CONTACTS,
D-SUBMINIATURE
CINCH DEH-9S MOUSER
ELECTRONICS
538-DEH-9S 1
604 . MALE SCREW
LOCK WITH
"U" CLIP,
CONNECTOR
4-40,
0.250" L
TYCO/AMP 5205980-1 MOUSER
ELECTRONICS
571-5205980-1 2
605 . HOOD,
CONNECTOR
. TYCO/AMP 207467-1 MOUSER
ELECTRONICS
571-2074671 2
606 . CORD,
POWER
3 18-GAUGE,
41 x 34
STRAND
CONDUCTORS,
SVT JACKET,
10' L,
SHIELDED
KOBICONN 173-0621-E MOUSER
ELECTRONICS
173-0621-E 1


Parts Table 7 ^
Fixture Items
LINE ITEM DESCRIPTION VALUE MANUFACTURER

MANUFACTURER PART
NUMBER

SUPPLIER SUPPLIER
STOCK
NUMBER
QTY
701 STANDOFF 6-32 x
2.5" L,
HEXAGONAL,
ALUMINUM
. KEYSTONE 1825 MOUSER
ELECTRONICS
534-1825 4
702 STANDOFF 6-32 x
2.0"L,
HEXAGONAL,
MALE/FEMALE,
ALUMINUM
. KEYSTONE 8425 MOUSER
ELECTRONICS
534-8425 4











Drawing Index
(back to contents)

126 Theremin

Antenna

Brackets

Base

Component Locations

Insulated Solder Turret Terminal

Chassis Plate Hole Locations

Parameter Responses

Power Supply Lay-out

Power Supply Mounting Plate Hole Locations

Schematic (page 1)

Schematic (page 2)

Schematic (page 3)

Transformers




Text and drawings ©2002, 2003, 2005, 2008, 2010, 2013, 2014, 2015, 2017, 2019, 2020, 2021 by Arthur Harrison

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