Help with circuit to close a switch for a long duration before opening (approx.15min) SOLVED

I am looking to design an automotive (12v) based circuit that will close a switch when the circuit is powered up for approximately 15 minutes (+/-1 minute) before opening the switch until being reset (by having the car turned off and losing power). I considered using an RC circuit but I believe the time delay is to long to reliably use just RC. I am also looking into using a 4060 timer IC but do not have much experience with IC's and was wondering if a simpler device/circuit existed for such a long time frame.

The objective is to fool the ECU into thinking the user has the button depressed for up to approximately 15 minutes. (The long duration is because the time between the circuit being powered up and the ECU actually recognizing the input can be up to 15 minutes.) The device has to allow the sensing wire to go high after the specified time frame, otherwise the ECU will see the low input all the time and set a logic fault code ignoring future inputs.

If someone with a better understanding of long delay timer circuits could help me out I would be incredibly grateful!!

by dsabin2011
May 11, 2018

1 Answer

Answer by mikerogerswsm

Yes, a 4060 is a reasonably cost effective approach. Here is a circuit which is close to what you want. If using car power, remember that this is very noisy and use appropriate noise rejection and regulation.

ACCEPTED +1 vote
by mikerogerswsm
May 12, 2018

Thanks a lot mikerogerswsm for your reply!!

by dsabin2011
May 13, 2018

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