Improved RGB-Pi adapter for use with RGB-Pi OS.
Based on open schematic published by mortaca.
Original RGB-Pi documentation: www.mortaca.com/docs/wiki
Changes:
- Added VGA (DSUB-15) 15 kHz connector (Warning: 31 kHz VGA monitors not supported).
- Proper sync combiner, borrowed from from BKM-129X clone board, see also KabukiFlux's RGBpi cable sync mixer.
- Improved R-2R RGB DAC.
- PWM audio buffered with SN74LVC2G34 Dual Buffer Gate powered from PS7A2033 Ultra-Low-Noise LDO, with separate analog ground, in order to reduce Raspberry Pi internal power noise.
- Added 3.5 mm audio jack connector.
| Reference | Value | Footprint | Qty |
|---|---|---|---|
| C1,C2 | 100nF | 0805 | 2 |
| C8,C9 | 10uF | 0805 | 2 |
| U2 | SN74LVC2G34DBVR | SOT-23-6 | 1 |
| U3 | TPS7A2033PDBVR | SOT-23-5 | 1 |
| F1 | MF-NSMF012-2 | 1206 Bourns MF-NSMF012-2 0.12A 30V | 1 |
| J1 | Raspberry_Pi_4 | PinHeader_2x20_P2.54mm_Vertical | 1 |
| J2 | SCART-F | CS-102 (SCART-21S) | 1 |
| J3 | DE15 Socket / DSUB-15-HD / VGA | DSUB-15-HD_Socket_Horizontal P2.29x1.90mm EdgePinOffset3.03mm MountingHolesOffset4.94mm | 1 |
| J4 | SJ1-3535NG | CUI/Same Sky Device SJ1-3535NG | 1 |
| Q1 | MMBT3904 | SOT-23 | 1 |
| R1 | 120R | 0805 | 1 |
| R2,R3 | 1K | 0805 | 2 |
| R6 | 100R | 0805 | 1 |
| R7 | 10K | 0805 | 1 |
| R8 | 1K | 0805 | 1 |
| R9 | 470R | 0805 | 1 |
| RN1,RN2,RN5,RN8 | R = 240R or 300R 1% | Resistor Array 4x0603 | 4 |
| RN3,RN4,RN6,RN7,RN9,RN10 | 2R = 475R or 604R 1% | Resistor Array 4x0603 | 6 |
Optional (SCART 5V->12V Converter for Status & Aspect Ratio switch):
| Reference | Value | Footprint | Qty |
|---|---|---|---|
| C5 | 100nF | 0805 | 1 |
| C3,C4 | 220nF | 0805 | 2 |
| C6,C7 | 4.7uF | Tantalum EIA-3528-21 / Kemet-B | 2 |
| U1 | ST662A | SO-8_3.9x4.9mm_P1.27mm | 1 |