Need a 5 sec. time delay off

Guys,
I have a circuit that is going through the normally open contacts (terminals 30 & 87) of a relay. These wires feed an engine idle-up control. I'm controlling the coil of the relay with the lock button on my FOB. My FOB has a 3 second pulse. The circuit works great to idle-up the engine (I sometimes have to push lock twice to increase the idle speed as much as I want).

Now, I want to build this into an automatic system - in other words, I don't want to have to push the lock button on the FOB manually to idle-up the engine (although this will also remain functional).   

I want to build a circuit that has a constant input (it's a 12V+ input fed from the alternator when engine starts and runs), with a 5 second output. I want the relay to become energized as it currently is (when the engine starts), then turn off after 5 seconds.

Can someone please send me a diagram for building a 5 second time delay off relay? I'm unsure of the correct size/value of capacitor and resistor to use to get the 5 seconds of on time delay off that I desire.

Thanks!

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The Badger

Can someone please send me a diagram (or direct me to a website) for building a 5 second time delay off relay?
I'm unsure of the correct size/value of capacitor and resistor to use to get the 5 seconds of on time
(delay off) that I desire from the relay.

In other words, I simply want to build a relay with a constant or switched 12V+ input, but only 5 seconds of output. The relay becomes energized, then opens after 5 seconds.

Help appreciated.

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The Badger

You can buy one already made.

PAC TR-7, or DEI also makes one, but I can't remember the number.

I did a search for the DEI unit,
Does 528T sound right?
Looks like a very versatile unit.
Thanks for the info.

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The Badger

The PAC TR-7 is a programming nightmare !! I hate those things !!

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Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA

Pretty easy to make one up, use a BS170 MOSFET to drive the relay coil, with an inline cap to drive the transistor high briefly. Then a pulldown resistor attached from the gate to ground turns it off after your time delay. I'll draw it up later and post it-

Here is is-


Just use a bigger cap or resistor to get a larger on time, and vice versa.
This assumes your (+) trigger input is at least 5 seconds; if you want it to output the same pulse even with a short trigger, then the circuit would need some mods. Since you said it would be constant, I figure it won't be a problem.

It won't turn on again until the input goes to ground, and then goes back up; then the relay should kick in for another time period.
Send me a postage stamp if you need a transistor-

That board looks pretty useful, how much does it go for? Seems like a lot of infrastructure for this purpose though-

Seems like the edit feature comes and goes on this board- if you use a polarized cap, the polarity should be switched as in this updated diagram-

Guys,
Thanks for the ideas and options.
After doing some testing, I've found that I need a 3 second output (instead of 5 seconds).

So, dualsport, what components/values, etc., do I need to change or modify in the above (updated) diagram to get a pulsed ouput to hold the coil of the relay between 2.75 minimum & 3 seconds max?

(Also, bravesirrobin, thanks for the info on the ELK-960).

Thanks!

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The Badger

See PM-