A (slightly) enhanced version of the original Voltage Blaster by PhilsComputerLab and Necroware here.
Enhancements:
- Diodes protect regulator from reverse polarity and reverse bias. Prevents soundcard-frying over voltage.
- Four LEDs show presence of the four main power rails on the ISA bus.
- Dual copper heatsink pads embedded into PCB design to keep regulator cool.
- Jumper to disable Voltage Blaster without removal. Can be used to verify lack of (-)5V on ISA bus.
The datasheet for the 79xx series negative regulators strongly recommend two protection diodes. PCs get shutdown suddenly and sound cards have lots of capacitance. The exact two situations described here.
Bill of Materials
| Item | Qty | MFG Part Num | Mouser Part Num |
|---|---|---|---|
| Neg 5V Linear Regulator | 1 | MC79M05CDT | 863-MC79M05CDT |
| 22uF 35V Electrolytic Capacitor | 2 | 860010572003 | 710-860010572003 |
| 5mm Red LED Diffused | 4 | WP7113ID | 604-WP7113ID |
| 330R Metal Film Resistor 1% | 2 | MFR-25FRF52-330R | 603-MFR-25FRF52-330R |
| 1K Metal Film Resistor 1% | 2 | MFR-25FRF52-1K | 603-MFR-25FRF52-1K |
| Schottky Diode 40 Volt 1.0 Amp | 2 | SB140-E3/73 | 625-SB140-E3/73 |