Same problem than John here: trying to use the library without much idea about these aValues. In my case it is a position control of DC motor and encoder.
A very cheap and easy to build Theremin for only 50$
- Only an STM32 evaluation board, 2 oscillators and some knobs and switches needed.
- Excellent audio quality: 16/24bit audio DAC with headphone amplifier
- Can load waveforms with Theremin sound directly from an USB stick
- Very fast autotune: 1sec
The STM32F407G-DISC1 evaluation board can be used.So you need only 2 additional oscillators and some potentiometers and switches.
Schematic
(Values of pitch oscillator)
Layout
The oscillators can be built up on a breadboard:
Bill of material
| Component | Pitch | Volume | Price |
|---|---|---|---|
| C1 | 150pF | 180pF | 0.05$ |
| C2 | 150pF | 180pF | 0.05$ |
| C3 | 330pF | 390pF | 0.05$ |
| C4 | 1µF | 1µF | 0.05$ |
| R1 | 2M2 | 2M2 | 0.05$ |
| R2 | 1k | 1k | 0.05$ |
| R3 | 10R | 10R | 0.05$ |
| IC1 | CD4069UBE | CD4069UBE | 0.48$ |
Suppliers:m: www.mouser.comf: www.farnell.com / www.newark.comd: www.digikey.com
L1 should be an air-coil with 1mH. Eg. 200 windings of 0.15mm wire on a core with 40mm diameter.
Use http://hamwaves.com/antennas/inductance.html for other diameters.
Pin maps
| Name | PIN Name | Connector | Description |
|---|---|---|---|
| GND | GND | P1 | Ground for oscillators and potentiometers |
| VDD | VDD | P1 | 3V supply for oscillators and potentiometers |
| PITCH_OSC | PE9 | P1 | Signal from pitch oscillator |
| VOLUME_OSC | PE11 | P1 | Signal from volume oscillator |
| ANALOG_1 | PA1 | P1 | Analog input from volume potentiometer |
| ANALOG_2 | PA2 | P1 | Analog input from zoom volume potentiometer |
| ANALOG_3 | PA3 | P1 | Analog input from shift pitch potentiometer |
| ANALOG_4 | PC4 | P1 | Analog input from zoom pitch potentiometer |
| ANALOG_5 | PC5 | P1 | Analog input from waveform potentiometer |
Connect an extra 100nF capacitor under each potentiometer from the potentiometer output to GND.
Auto-tune
The blue button on the STM32 discovery board starts the Auto-Tune procedure.
You can also use an additional button and connect it to:
| Name | PIN Name | Connector | Description |
|---|---|---|---|
| VDD | VDD | P1 | 3V supply auto-tune button |
| Auto-tune | PA0 | P1 | Signal from auto-tune button |
Pitch LED display
Optional display to show the current played note one a piano like display.
Connect 3mm LEDs with a series resistor of 100R to these PINs and connect allcathodes of to GND:
Stm32 Dev Board
| Name | PIN Name | Connector | Description |
|---|---|---|---|
| PITCH LED 0 | PE12 | P1 | Note c |
| PITCH LED 1 | PE14 | P1 | Note cis |
| PITCH LED 2 | PE15 | P1 | Note d |
| PITCH LED 3 | PB11 | P1 | Note dis |
| PITCH LED 4 | PB12 | P1 | Note e |
| PITCH LED 5 | PB13 | P1 | Note f |
| PITCH LED 6 | PB14 | P1 | Note fis |
| PITCH LED 7 | PB15 | P1 | Note g |
| PITCH LED 8 | PD8 | P1 | Note gis |
| PITCH LED 9 | PD9 | P1 | Note a |
| PITCH LED 10 | PD10 | P1 | Note b |
| PITCH LED 11 | PD11 | P1 | Note h |
Power supply
The STM32 discovery board must be supplied by 5V (100mA). It is importand that the GND is connected to earth (PE). If a normal wall adapter is used, there must be an extra connection to earth (PE).
The best power supply would be a linear one like this: https://github.com/gerdb/tinnitus32/wiki/Power-supply
USB-stick with sound file
It's possible to store a *.WAV or a *.C file on an USB-stick and use it as sound source for the theremin.
WAV file
The file name must be WAV1.WAV and it must contain 1 periode of a sound sample. File format must be WAV (Microsoft) and the data format signed 16 bit PCM with only one mono track. Use Audacity to export it. https://www.audacityteam.org/
C file
The file name must be WAV1.C and it must contain 1 periode of a sound sample. File format must be the same as the Audio Wavetables from the Open.Theremin V3 project. http://www.gaudi.ch/OpenTheremin/index.php/download/audio-wavetables
Programming software for STM32
You find the binary file in the 'Binary' folder. Download the tinnitus project as ZIP
Program the STM32 board with the STM32CUBEPROG tool.
Case and front panel
As case a wooden wine box could be used.
The cheapest way for a professional looking front panel would be to use the service of a sign manufacturer. For example:https://www.digitaldruck-fabrik.de/werbeschilder/hart-pvc-polystyrolplatte.aspx
Price of a 380x110mm front panel is about 4€ or 5$
You can use the template under hardware/Frontpanel, but you have to adapt the size of the front panel file to your wine box. Use eg. https://inkscape.org
An easy to build Theremin for only 50$
- Only an STM32 evaluation board, 3 oscillators and some knobs and switches needed.
- Excellent audio quality: 16/24bit audio DAC with headphone amplifier
- Can load waveforms with Theremin sound directly from an USB stick
- Very fast autotune: 1sec
The STM32F407G-DISC1 evaluation board can be used.So you need only 3 additional oscillators and some potentiometers and switches.
Schematic
Layout
Stm32 Eval
The oscillators can be built up on a breadboard.With THD components:
Or with SMD components:
Bill of material
| Component | Volume 1 | Volume 2 | Pitch | |
|---|---|---|---|---|
| C1 | 1µF | 1µF | 1µF | ceramic capacitor |
| C2 | 470pF | 470pF | 470pF | ceramic capacitor |
| C3 | 33pF | 68pF | 33pF | ceramic capacitor |
| C4 | 2.2nF | 2.2nF | 2.2nF | ceramic capacitor |
| R1 | 10R | 10R | 10R | resistor 1% |
| R2 | 22k | 22k | 1Meg | resistor 1% |
| R3 | 100R | 100R | 100R | resistor 1% |
| IC1 | CD4011UBE | CD4011UBE | CD4011UBE | Quad NAND |
L1 should be an air-coil with 2.5mH, 3mH and 4mH.Eg. x windings of 0.15mm wire on a core with 50mm diameter.Picture below shows all 3 coils with different number of windings.
Use http://hamwaves.com/antennas/inductance.html for other diameters.
Pin maps
| Name | PIN Name | Connector | Description |
|---|---|---|---|
| GND | GND | P1 | Ground for oscillators and potentiometers |
| VDD | VDD | P1 | 3V supply for oscillators and potentiometers |
| PITCH_OSC | PE9 | P1 | Signal from pitch oscillator |
| VOLUME_OSC | PE11 | P1 | Signal from volume oscillator |
| ANALOG_1 | PA1 | P1 | Analog input from volume potentiometer |
| ANALOG_2 | PA2 | P1 | Analog input from zoom volume potentiometer |
| ANALOG_3 | PA3 | P1 | Analog input from shift pitch potentiometer |
| ANALOG_4 | PC4 | P1 | Analog input from zoom pitch potentiometer |
| ANALOG_5 | PC5 | P1 | Analog input from waveform potentiometer |
Connect an extra 100nF capacitor under each potentiometer from the potentiometer output to GND.
Auto-tune
The blue button on the STM32 discovery board starts the Auto-Tune procedure.Connect an external button to:
| Name | PIN Name | Connector | Description |
|---|---|---|---|
| VDD | VDD | P1 | 3V supply auto-tune button |
| Auto-tune | PA0 | P1 | Signal from auto-tune button |
Pitch LED display
Optional display to show the current played note one a piano like display.
Connect 3mm LEDs with a series resistor of 100R to these PINs and connect allcathodes of to GND:
| Name | PIN Name | Connector | Description |
|---|---|---|---|
| PITCH LED 0 | PE12 | P1 | Note c |
| PITCH LED 1 | PE14 | P1 | Note cis |
| PITCH LED 2 | PE15 | P1 | Note d |
| PITCH LED 3 | PB11 | P1 | Note dis |
| PITCH LED 4 | PB12 | P1 | Note e |
| PITCH LED 5 | PB13 | P1 | Note f |
| PITCH LED 6 | PB14 | P1 | Note fis |
| PITCH LED 7 | PB15 | P1 | Note g |
| PITCH LED 8 | PD8 | P1 | Note gis |
| PITCH LED 9 | PD9 | P1 | Note a |
| PITCH LED 10 | PD10 | P1 | Note b |
| PITCH LED 11 | PD11 | P1 | Note h |
Power supply
The STM32 discovery board must be supplied by 5V (100mA). It is importand that the GND is connected to earth (PE). If a normal wall adapter is used, there must be an extra connection to earth (PE).
The best power supply would be a linear one like this: https://github.com/gerdb/tinnitus32/wiki/Power-supply
Programming software for STM32
You find the binary file in the 'Binary' folder. Download the tinnitus project as ZIP
Program the STM32 board with the STM32CUBEPROG tool.
Case and front panel
A wooden wine box or a bamboo box for the kitchen (both about 10$) can be used as a case for the timbremin.
The cheapest way for a professional looking front panel is to use the service of a sign manufacturer. For example:https://www.digitaldruck-fabrik.de/werbeschilder/hart-pvc-polystyrolplatte.aspx
Price of a 380x110mm front panel: 5$
You can use the template under hardware/Frontpanel, but you have to adapt the size of the front panel file to your case. Use eg. https://inkscape.org