Theremin Phoenix volume & pitch control

3.09.14

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Phoenix
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Developing New Control Board
3.03.14
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Besides a Pitch Only Theremin this can also be a Stand Alone Volume Control

Instantly make your right handed theremin a lefty. This could also be used with all those pitch only theremins. The results using audio sound from this radio demonstration shows how the Phoenix operates distortion free with excellent shading.

Radio Audio .mp3 100k
12" Volume Shading Demo

Learn About the Phoenix Features

How to Receive This"PCB" Free

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Construction begins with Step #1

Complete Schematic found here

Heterodyne Oscillator / Theremin Osc Audio Preamp - Pitch Output or Volume Control
3" x 3" 5.2" x 3"

Commercial Board Date 1.24.13 - Must Read modifications that have been added since.

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Construction begins with Step #1
Order your parts from this page

Complete Schematic found here

A Universal Volume Control or Pitch Only Theremin Together the Worlds Finest Theremin
Etch Your Own Circuit Board Info	Drill Sizes PDF If you etched your own board
PDF Top Silkscreen 410k	PDF Bottom Copper Traces 180k
The above Circuit Board PDF's are most recent as of - 3.08.14 The latest Modifications are on this etch-your-own, not on commercial PCB

PDF Data Sheets - TL082 - LM358 - TLC555 - NE555 - VTL5C1 - V0618a - IF Coil
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Start Building	Tuning	Peripherals
Step #1 Order your parts from this page	3 x 3 Board Test Tune With AM Radio	Lev Antenna For Perfect Pitch Field Linearity
Phoenix Features There Are Many	Pitch Control Setup & Proper Wave Shape	Theremin Enclosure Template to Drill Wood Holes
Phoenix-Cables Bargain TRS Cables & Wall-Wart	Volume Control Setup & Proper Wave Shape	Theremin Pitch Tuner Freeware for Analysis
Things Not at Mouser Accessories	Excel Parts List PDF Notes & Updated values!	Spectrum Analyzer Freeware for Analysis
Modifications to Add After PCB was Ordered *	Ideas & Components Future Developments	Minimum Pitch Parts Start of Build or Pitch Only Theremin
You are on the Private Home Page!	Receive The PCB Free	Setup Earth Ground The Black Box
You are on the Private Home Page!	Dragonfly The Secret Hybrid	Volume Enhancements Torch - Preview Fade - Volume Step

Check Here First For New Pages

Notes About Board:

* V1 on the Volume Control Board is a VTL5C1 Vactrol, the NSL32SR3 might be a good substitute. There are pads for a H11F1M which has distortion on the quiet side, use as a last resort replacement for the Vactrol. These are variable resistors, the heart of volume control.

From the Pitch board use Out-2B or Output-2 as a Pitch Preview. Use a headphone amp or one side of your stereo pre-Amp EQ to buffer. If the Control Board is used this has an on board headphone amplifier.

Pitch Board, the left side A B C D are wire terminals together labeled as T1. A & D are tied to the IF transformer shields L1 & L2. L1 & D are are tied to ground through Pot-5 so varying the resistance can alter the static coupling between the oscillators. Use a copper clad ground plate under the L1 on the 3 x 3 section. This connects directly to ground at C or better yet at D for more coupling effect on the wave shape by Pot-5 control.

Note: Pitch Board, connecting the L2 IF shield terminal A to ground may dampen the inside linearity of the Lev Antenna response in the pitch field. Leave unconnected.

B is direct to the detector/mixer diode. For Pitch wave shape experiment by mounting a short 3" (75mm) wire with the opposite end floating in the air near Q1 (loose coupling). This can have interesting affects on wave shape and increases the signal level and how the overall Pitch sounds.

Pitch Board, on the right side of the main board T6 is for power or use the 1/8" jack with a 3.5mm plug from the wall-wart adaptor. I use a earth ground mix box from the power strip where the ground taken from the third prong or off the F-connector on some AC Power Strips. From the mix box I run a 6' 3.5 mm cable to the T6 (2-1-5) power jack on the theremin Pitch board. The jack is wired to use either a mono or stereo cable.

Around the IF Cans and other pads are an x ignore them, these are markers for experimental modifications.

Volume Control Board, for Click Free Mute place a closed switch across Terminal T5 on the Volume Board near the Vactrol.

The 12 volts dc regulated power can be connected in three different locations. One would be the Pitch board T6/Jack, the Volume board T6/Jack or at the Black Box placed in the center of the J2 cables between the pitch and volume boards. I have a new voltage regulator to consider using, need only one for Volume and Pitch Boards together.

Never connect J2 to anything other than a J2 jack and cable. It is powered and could damage your sound card if plugged into it!

I have not drawn a full schematic for this board but the design principles should be obvious studying the values and following the green copper traces. (If you want to draw a schematic and sign it, excellent)

The left side L1 & L2 along with Q1 & Q2 generate the pitch and reference frequency which are detected at the signal diode D2. The U1 OP amplifier increases the signal 100x which then drives the Q3 transistor which drives the 555. The signal driving the 555 is monitored using Red LED-2.

On the volume control board the oscillators are setup for a more spiky wave form, this transforms into pulse width modulation (PWM) which varies from the distance/response to your hand varying the RF oscillator frequency. This PWM controlled 555 output changes the Vactrol internal LED intensity along with the external green LED-1 for an excellent volume response. The volume oscillator control frequency range used for volume shading is about 50 hz to 500 hz.

You must use a good earth ground with theremins, get it from somewhere!

Use only one ground source to help avoid ground loop hum! A "ground loop isolator" on the theremin output is recommended.

A wall-wart can be hard to find with a ground terminal. On the right side of my board the power input 1/2 wave diode and 9v regulator will accept 12v dc regulated, Visit how to ground a wall-wart. The D1 diode protects against reversed polarity.

Here in the USA an extension cord could bring the ground from the wall using a power strip with a green LED ground indicator and tapped into with a creative plug setup for ground access. Visit how to ground a walwart.

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