There are many commercially available Capacitoy Discharge Units on the market, but where's the fun of not making your own.
The CDU-2 described on the excellent Talking Electronics web site provides the basis for the capacitor discharge unit. The following circuit schematic was used:
The bill-of-materials is:
| Qty | Item | Rapid Code |
|---|---|---|
| 2 | 1000 uF Radial Electrolytic | XX-XXXX |
| 3 | Rectifier Diode | XX-XXXX |
| 1 | BD679 Darlington Transistor | XX-XXXX |
| 1 | 1K resistor | XX-XXXX |
| 4 | 2K2 ¼W resistor | XX-XXXX |
| 1 | 3mm LED (red) | XX-XXXX |
| 1 | 25mm X 64mm stripboard | 34-0500 |
| Some 7/0.2 wire |
The final stripboard looked like this: