Assembly Guide
Populate Back Side SMT Components
- Schottky diodes D2, D3, D6, D7
- Ferrite beads (or 10R): R20, R21
- BJTs Q1-Q3
- SMT LED D1
- ICs U1-U3
- SMT capacitors C2, C1, C5-C8
- SMT resistors R1-R19
Populate Front Side THT Components
- IDC header J6
- Electrolytic capacitors C3 & C4
- Programming header J5
- Mono jacks J1-J4
- Potentiometers RV1 & RV2
Populate red 3mm LEDs D4 & D5 with face plate mounted. Leads need to be formed to a 90 degree bend; watch the orientation.
Programming and Test
Open the firmware project with PlatformIO and connect a USBISP to the programming header on the PCB (check the orientation relative to the ground pin). Flash the firmware.
Test by sending gate pulses to the input. The LEDs will visually indicate the timing of the delayed pulses, or an oscilloscope can be used to check shorter delays.
BOM
| Reference | Qty | Value | Footprint |
|---|---|---|---|
| C1,C5,C6,C7,C8 | 5 | 100n | 0805 |
| C2 | 1 | 10n | 0805 |
| C3,C4 | 2 | 10u | Radial D5.0mm P2.50mm |
| D1 | 1 | Red LED | 0805 |
| D2,D3,D6,D7 | 4 | B140Q-13-F | SMA |
| D4,D5 | 2 | Red LED 3mm | LED D3.0mm |
| J1,J2,J3,J4 | 4 | WQP-PJ323M | WQP-PJ323M |
| J5 | 1 | Pin header | 02x03 P2.54mm Vertical |
| J6 | 1 | IDC header | 02x05 P2.54mm Horizontal |
| Q1,Q2,Q3 | 3 | BC847 | SOT-23 |
| R1,R11,R17 | 3 | 4k7 | 0805 |
| R2,R13,R14,R16,R19 | 5 | 10k | 0805 |
| R3,R4,R6,R7,R8,R9,R10 | 7 | 100k | 0805 |
| R5,R12,R18 | 3 | 1k | 0805 |
| R15 | 1 | 150k | 0805 |
| R20,R21 | 2 | 10R | 0805 |
| RV1,RV2 | 2 | B100k | Bourns PTV09A Horizontal |
| U1 | 1 | ATtiny13A-S | SOIC-8 3.9x4.9mm |
| U2 | 1 | TL074 | SOIC-14 3.9x8.7mm |
| U3 | 1 | AMS1117-5.0 | SOT-223-3 |