Hi im not new to electronics but im not that knolagable

I am using a dual Coil latching relay to turn an ignition on and off. Using a rfid to turn on and a pulse from another device to turn it off. I also want it to turn off after like 15-30 mins. Someone sugested a compacitor but if I understand correctly that will charge up to a much higher voltage and release it at one which would overload the relay coil. The simpler the better someone also said I would have to use a microcontroler. I am considering haveing the relays mounted on a pcb board and would like to add the timer feature built it rather than trying to add it on later. My though was a compacitor and something that would only allow the 12v 100mA through and ground the rest. (to empty the compacitor)

 

When you type "compacitor," do you mean "comparator" or "capacitor?"

 

capacitor, sorry my spelling is horrable. ya after a period of 15 mins I need a 1-2 second pulse.

 

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