Assembly Guide
Build
Note
The collector lead of Q1 should be cut off at the case before installing.
- Diodes D3 & D4
- Horizontal resistors R1 (or ferrite), R16, R27, R28, & R30
- Sockets for U1 & U2
- Ceramic capacitors: C3-C5, C9-C11, C17-C22 (no C15 or C16)
- BJT Q1 - ensure collector lead is cut
- Trim pots RV1 & RV3
- Film capacitors for the filter network: C6-C8 & C12-C14
- Remaining resistors (R2 may be a ferrite to match R1 if desired; no R12 or R23)
- IDC header J1
- Mono jacks J2-J6
- Grain potentiometer RV2
As a final step, attach the faceplate.
Calibration
- Adjust RV1 to get 10Vpp at the white noise output (rare excursions above 10Vpp are likely OK).
- Adjust RV3 to balance the grain outputs between positive and negative spikes. In my experience biasing it towards 2/3 negative and 1/3 positive is good.
BOM
Note
All resistors are 5% tolerance. All capacitors are ceramic except for the 2 10uF decoupling capacitors (electrolytic). RV1 and RV3 are 6mm trim pots.
| Reference | Value | Qty | Notes |
|---|---|---|---|
| C1,C2 | 10u | 2 | |
| C3,C17,C18,C19,C20,C21,C22 | 100n | 7 | |
| C4,C10,C11 | 22p | 3 | |
| C5 | 1u | 1 | |
| C6,C12 | 10n | 2 | |
| C7,C13 | 2n2 | 2 | |
| C8,C14 | 470p | 2 | |
| C9 | 1n | 1 | |
| D1,D2 | 1N5819 | 2 | |
| D3,D4 | 1N4148 | 2 | |
| J1 | 10P IDC Header | 1 | |
| J2,J3,J4,J5,J6 | WQP-PJ323M | 5 | Horizontal |
| Q1 | BC547 | 1 | cut collector lead |
| R1,R2 | 10 | 2 | alt.: ferrite |
| R3 | 2M2 | 1 | |
| R4 | 470k | 2 | |
| R5,R7,R14,R19 | 22k | 4 | |
| R6,R13,R17,R27,R29 | 100k | 5 | |
| R8 | 150k | 1 | |
| R9,R20 | 330k | 2 | |
| R10,R18,R21 | 68k | 3 | |
| R11,R22 | 15k | 2 | |
| R15,R16,R24 | 1k | 3 | |
| R25,R26 | 10k | 2 | |
| R28 | 120k | 1 | |
| R30,R31,R32 | 4k7 | 3 | |
| RV1 | B470k | 1 | 6mm trimmer |
| RV2 | B100k | 1 | |
| RV3 | 50k | 1 | 6mm trimmer |
| U1 | TL074 | 1 | |
| U2 | TL072 | 1 |