I apologize in advance if this was asked before but I searched and could not find anything.
I'm trying to create a circuit that will kill the fuel pump and basically would automatically enable once the car was shut off. Pretty much I would like to have a momentary switch which would be power by the switched 12v in the car and a relay that it would drive. Simply speaking I would get into the car, put the key in and put it in the "RUN" position, hit this switch once and it would active a relay which would enable the fuel pump. Then the car could be started, once the car would be shut off, the power would no longer be supplied to the relay and it would open up again, therefore turning off the fuel pump. The problem I'm running into is I cannot figure out a way to keep the relay closed (proper term?) using a momentary switch.
basically the question is how can I keep the relay closed just by using a momentary switch or perhaps pulsing it? It's actually a 2 piece problem as it's supposed to turn off again once the car is turned off.
I guess i'm thinking more along the lines of a rear window defroster switch, usually it works as follows:
Press it once, it turns on the defroster, which stays on until it overheats or you manually turn it off. But once you shut off your car it automatically turns off anways, no matter what.
Thanks.
Basic Starter Kill will do the same thing ...WithOUT the need for a extra Switch. Can be done everytime you turn on Ignition Key....would activate Relay for Fuel Pump. Turn Ignition OFF and Relay shuts Fule Pump to "OFF"
If you HAVE to have extra switch....Use a LATCHING Relay
-------------
MO
Don't Learn from Others Mistakes
You Might Be the One That Knows.
This might work. Try bench testing first. Put a light bulb or motor or something inplace of the fuel pump.
LOL. I love this site! It has everything already there!
check out
https://www.the12volt.com/relays/page5.asp and use momentary to constant 12v (+) this will solve your prob. you can also switch configs to get a constant (-).its all there on 12 volt .com check that link out
-------------
JUST ONE MORE AMP!!!
hu,alpine cva 1005/dva 5205
sound processor,symmetry(first one).
sub amp,power 1000 the terminator.(1992).
subs,spl comp dual 1 ohms.
punch 150hd on a 10" ev.
alotofhighs
That's true, if you do go for an ignition or fuel cutoff circuit, you need to be a lot more careful with the installation and selection of a high reliability relay that has rated well above what the circuit is expected to draw.
Solder and heatshrink the connections, no quickie methods.
Maybe you could wire in a parallel relay for redundancy, just to make sure.
Only reason I might go for that rather than starter kill is that it's obvious to the thief what the problem is when the car doesn't crank, and he could just go straight for the starter, which will be in a known location. Lots more variables to keep him guessing if it cranks but just won't fire.