(BTW, I'm no expert either, so take my advice with a grain of salt and don't blame me for anything :) )Quote:
Originally Posted by fire
See that's where you lose me. Don't see how you can do that with one monostable, not with that circuit anyway.
When you pull the trigger low, the output goes high for the time specified and then it goes low again.
So when the car starts, the trigger and reset go high, so the output should be low (sinking)
If the relay is grounded to the output, then the relay will close when you turn the key.
Now when you turn off the car, it triggers the pulse which makes the output go high (sourcing current), meaning the output and battery + will have the same potential (or almost anyway), so no current flows, which means the relay clamps off. addition: so after your 30 seconds, the relay comes back on!
If the relay isn't grounded to the output, but is being driven by it (meaning one side of coil is at output, one at ground), then what should happen is, the car starts, the trigger is high, the output is low and the relay doesn't open at all until you remove ACC.