Automated capacitor precharge circuit

You could go a little old school and use a light bulb and an ignition switch similar to your car in place of the resistor, regulator, and possibly the relay. The lightbulb would be a standard 120V incandescent lamp. (Thinking oven/refrigerator lamp) Dynamically the lamp would provide a HIGHER resistance when it is lit (charging) and a LOWER resistance as it goes out (charged). Initially there would be a LOW resistance spike, but that's what lamps do from a cold start.

The idea with the ignition switch it has TWO positions you need to use ... One when you initially stick the key in and partially turn it FORWARD. This would be the "charging" period through the LAMP. The other (momentary) STARTING position would engage a RELAY and latch it as long as power is provided through the ignition switch. Or if you wanted to eliminate the relay, turning the key BACK (as you would normally do in a car if you just wanted to listen to the radio without the Engine running) ... this position would simply short out the LAMP.

Note: In the BACK option make sure you check the current capability of the ignition switch.

Beau Schwabe said:

You could go a little old school and use a light bulb and an ignition switch similar to your car in place of the resistor, regulator, and possibly the relay. The lightbulb would be a standard 120V incandescent lamp. (Thinking oven/refrigerator lamp) Dynamically the lamp would provide a HIGHER resistance when it is lit (charging) and a LOWER resistance as it goes out (charged). Initially there would be a LOW resistance spike, but that's what lamps do from a cold start.

The idea with the ignition switch it has TWO positions you need to use ... One when you initially stick the key in and partially turn it FORWARD. This would be the "charging" period through the LAMP. The other (momentary) STARTING position would engage a RELAY or if you wanted to eliminate the relay, turning the key BACK (as you would normally do in a car if you just wanted to listen to the radio without the Engine running) ... this position would simply short out the LAMP.

Note: In the BACK option make sure you check the current capability of the ignition switch.

Click to expand...

I've thought about that. I have a key and a separate momentary button switch already, so I might just use those. But The idea of an automatic circuit is pretty cool to me so I've not totally abandoned that idea yet.

Well, I have a solution. I decided I'm going to have other components run by an Arduino in the circuit, so I'll have the key-switch turn on the precharge circuit and activate the Arduino, then after a set time the Arduino will trigger a relay to bypass the precharge circuit. And then, when the key is turned off, the Arduino will turn off which will turn off the relay and shut everything off. Bam. Very simple, very easy, very cheap.