Electronics question....or two

I would like to design a circuit that when triggered with a one amp signal that would last for thirty seconds max, would trigger a relay to run for 2-4 minutes. It is called an off delay relay. I have found some stuff on the internet but not sure how it should be wired or how to assemble a board to make it work, or where to just find a circuit. It should work like when you turn off your ignition but your lights stay on for a minute of two.
The things I have found are for A/C units in the 12 volt range as seen here:





I understand the concept, just need some help.

Bill

HI Bill Is this what your looking for.
Click here: Headlights Timer by BC547,BC327 | Circuit Project Electronic

Could also "butcher" a ventilation fan for a bathroom

A lot of these run on 12 v and have a built in delay timer with an adjustment button so it can be left to run on for 1 to about 10 minutes

Is it worth trying to re-invent the wheel?

Ian

Hey Bill,

I think you have that answer right there on the VTM2 spec sheet. Buy one of those devices and you can wire it as shown on the bottom left of the sheet. The Load there will be your lights on 3 and 1, input voltage will just be a 12V supply on 1 and 2, and you'll have it wired to your ignition there on terminals 6 and 7. You change the value of the resistor to change the delay time and they give you the formula.

Or build the circuit that Wally posted for you but I imagine the VTM@ can be found cheaply enough to not be worth your time unless you are an electronics hobby guy.

EDIT:
Newark has them, $36.

http://www.newark.com/tyco-electronics-agastat/vtm1acd/time-delay-relay/dp/98F9870



Ron

Thanks guys,
I understood it, just needed someone to point me in the right direction. If this works out I will post it on the forum. No, it's not for the interior or exterior lights, although it is an idea. I am still working on the gremlins with the car. It hasn't undergone its maiden voyage yet due to these things popping up. Have fired it up several times on the jack stands. Can't believe how good it sounds. Did it yesterdday and when I turned it off, there were 4 guys standing in the driveway. They were working on the gutters next door and wanted to see what was making their ladders shake!!! The Panasonic camcorder I borrowed(DVD) won't read on my laptop. So until I solve that one, I can't post it. Isn't life wonderful?

Bill

Bill, I know the felling, I started my car for the first time a week ago and it really was amazing. I've also had my share of teething issues but the wait is worth every moment because the first time you drive it you will not believe you created such an insane and crazy thing. Don't get too discouraged if you only make it a few miles and get towed home the first time, just do it late at night and not too far from home. Wonder how I know that. Good luck, you’ll love it.

Your lights will draw more that 1 amp, maybe as much as 10 Amps. 1 amp appears to be the safe current limit of the module. So here's what you do. Use the load lug output of the module to power a headlight relay. Here's how it it wired.

Use the VTM2 as it's circuit diagram indicates except that instead of running the "load" wire to the headlights directly and thus pulling all of the current needed to run the lights through the VTM2 module, run the "load" connection to the 12VDC + terminal of a headlight relay coil. You will need to ground the other side of the coil but just follow the relay install directions for it and you will be OK. Then run a different 12VDC power wire through the power contacts of the HL relay to the headlights. If your car has a HL relay in it already then just use it in place and power it's coil as described. Put a fuse in the VTM2 circuit that supplies 12VDC to the module.

Now you have the original fuse that protects the headlight circuit and another one that protects the VTM2 module circuit.

If it was my car I would put a bypass switch in the coil circuit of the headlight relay so that I could turn on the headlights without the VTM2 module if I wanted to in case of a module failure. A wire from the positive HL power post of the relay through a switch to the coil positive post of the HL relay will do it for you.