Re: [ihc] RE: Relaying George's power

[John Hofstetter <hofs@xxxxxxxxxxxx>]

On Jul 28, 2004, at 10:54 PM, Allan Ericson wrote:

> Okay. The short version: There's a wire that goes to the solenoid 
> during the
> run cycle. It has 12 volts on it when you start the engine. This 
> terminal is
> labeled "S" and is always present on a stock starter. On a points 
> ignition,
> there is also a terminal labeled "R" that also has 12 volts on it at 
> that
> time. That wire goes to the coil. Either wire will work to trigger a 
> relay
> during STARTING.
>
> During run, any wire that's hot with the key on can be used.
>
> The way to fire a relay with two separate feeds is to use DIODES. They 
> can
> be obtained at RADIO SHACK for a buck.
>
> Each feed gets a diode. The end without the stripe goes to the wire. 
> The end
> with the stripe goes to the (+) terminal of the relay coil. The 
> negative
> side of the relay coil goes to chassis ground or battery (-).
>
> Common diodes are part number 1N4001, 1N4002, 1N4003, and 1N4004. Type 
> 914
> will also work.
Concise explanation of how he can do it.

However, that wasn't his question. He wanted to know if an MSD unit 
would allow him to do the same sort of thing in addition to giving him 
another gadget for his truck. It will.

John