See general assembly instructions
All parts are available on Tayda (cart link, quick-order CSV).
See general components notes for more info about acquiring parts.
| Board | Reference | Part | Value | Source | Comment |
|---|---|---|---|---|---|
| Front | R1-R4 | Resistor | 33kΩ | Tayda | Should be ~5/7 times the resistance of RV2 & RV4. |
| Front | RV1-RV4 | Potentiometer | B50kΩ | Tayda, Thonk | Linear. Any value is fine. Determines the input impedance of the module, so a higher value will mean a better attenuation range for some inputs (100k might actually be better). |
| Front | J1-J4 | 3.5mm Jack | THONKICONN (a.k.a PJ398SM or PJ301M-12) | Tayda, Thonk | |
| Front | D1-D11 | LED | 3mm bipolar | Tayda, ebay | This is a bipolar/bi-color LED. That means it is essentially two LEDs wired in opposite directions in the same package. Reversing the connection reverses the colors. When the module is outputting a positive voltage, the current will flow “forwards” through the LED, i.e. the square “cathode” hole towards the top of the module will be negative and the round “anode” hole towards the bottom of the module will be positive. When the module is outputting a negative voltage, the current will be reversed. The LEDs I bought were red in their “forward” direction and green in reverse, so I put them in backwards to get a green light for positive voltages. If you only have normal unipolar LEDs, just solder another led or any diode in reverse across the legs to protect the LED from the reverse current. |
| Back | R5-R8, R11-R14 | Resistor | 100kΩ | Tayda | Any value 10k-100k is probably fine as long as they all match. |
| Back | R9, R16 | Resistor | 10kΩ | Tayda | Determines LED brightness. Any value between 220Ω-10kΩ might be appropriate depending on which LEDs you have and how bright you want them. |
| Back | R10, R15 | Resistor | 1kΩ | Tayda | Determines output impedance |
| Back | C1-C2 | Capacitor | 10uF | Tayda | Power supply noise filtering capacitors |
| Back | C3-C6 | Capacitor | 100nF | Tayda | Power supply noise filtering capacitors |
| Back | C7-C10 | Capacitor | 33pF | Tayda | Stabilizing cap for op-amps. Depending on the model of op-amps used, these probably aren’t strictly necessary. Should be proportionally larger if using smaller resistors for R5-R8. |
| Back | U1, U2 | Op-amp | LM324N | Tayda, DigiKey | Any quad op-amp would probably work here, as long as it follows the standard pinout and can handle 24V power supply. A TL074 would work fine, but it can’t handle rail-to-rail inputs, so it might give unexpected behavior if the input or output approaches -12V. Therefore, it is better to use a rail-to-rail-capable op-amp like the LM324. |
| Both | J5-J8 | Pin headers | 1x7, 1x8 | Tayda (Male, Female), Amazon | Solder the two boards directly together using the male headers or make them detachable using a male/female pair (recommended). |
| Back | J12 | IDC connector | 2x5 | Tayda | Eurorack power header. Can use two rows of male pin headers or (recommended) a shrouded connector. |
| Both | - | Standoffs | 2 M3x11mm standoffs with screws and nuts | Tayda: Offset, Nut, Screw | Holds the 2 PCBs together. Alternatively, use a long M3 bolt with some nuts on it. Obviously, if you are soldering the boards together the length would be different and could be omitted entirely. |