Table of Contents
Assembly
In order to assemble the device, the following parts are required:
| Parts Required | ||
|---|---|---|
| Component | Type | Description |
| R1 | ¼ Watt Resistor | Resistor for trigger voltage determination (value calculated above) |
| R2 | ¼ Watt Resistor | Resistor for trigger voltage determination (value calculated above) |
| R3 | ¼ Watt Resistor | 1KΩ used for the remote trigger activation pull-down |
| R4 | ¼ Watt Resistor | Current-limiting resistor for LED1 (Use ½ Watt for ~15-25v VCC and 1 Watt for 25+v VCC) |
| U1 | MC4323P11) | Overvoltage Crowbar Sensing Circuit (OnSemi/Motorola) |
| Q1 | 2N6504 | SCR (used to implement the crowbar) |
| LED1 | LED | Activation indicator LED, your choice, just select R4 accordingly |
| F1 | Fuse holder/clips | Fuse for circuit protection and your desired mounting style |
Soldering
When assembling and soldering components, observe proper ESD handling techniques. Place all parts in their respective locations, paying careful attention to the orientation of U1, Q1 and LED1. Orient the board so that you are looking at the top of it (the parts side, not the solder side) with the two large power input connections and F1 positioned on the left. The board should be oriented as shown here:
U1 (and its socket) should be mounted with the notch facing the top of the board. Q1 should also be mounted with its tab facing the top of the board, not facing the resistors. Pay careful attention to the handling of the LED1’s flat side, it should be oriented toward the right side of the board. The silkscreen markings on the PCB should also indicate the correct orientation for components where applicable. For the resistors, you have the choice of using thru-hole, surface mount (SMD), or a mix of the two.
Solder all components in place and verify your work, making sure all connections are sound and nothing is shorting, open, or anything else undesirable. When done, your work should resemble something like these:
If happy with your work, proceed to the testing page.