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Need Help With A 12 Volt Dc Project

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dlawn

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I am in need of some help in which I think I need some type of latching relays to do what I want.

This is using 12vdc from a regular car type battery.
What I want to do is by supplying a pulse of current turn some regular vehicle headlamps on and off each time the remote button is activated. Then with another button on my remote switch them between high and low beam. The temporary pulse of current needs to hold the function until the button is pressed again. The lights will draw about 25 amps.

I do want to be able to control some snow plow lights with the remote. I have 12 volt power cable from the vehicle to the plow and do not want to use wiring and a switch back to the cab of the truck. ANY help and sources for what I need would be greatly appreciated.
 
The plow is on the front of your car right? Why can't you just route the power cable into your car before it goes to the plow and have a switch sitting along the wire in the cabin?

Or you could put the relay as close to the cabin as possible and run two small wires out with a switch sitting in the cabin to drive the coils on the power relay.

All the wireless stuff seems all for nothing, more work, and less reliable...Why do you even need wireless? If it was something on the back end like a trailer or somethign I would understand, but this thing is on the other side of the windshield.

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For the remote, you can get little keychain things like this:
**broken link removed**

You can have a 12V->5V regulator piggyback off of the power cable to power the receiver.

To switch the lights you can use a normall open relay, a two-way latched relay, or a MOSFET.

You *might* be able to get a MOSFET that can pass 25A and have a gate threshold voltage that is low enough to be driven by the receiver. Since I'm pretty sure the receiver output does not latch, you would need a latching circuit to continue to drive the FET after you release the button. Same thing goes for the normally open relay, except it's slightly more annoying because now you have to latch a larger current.

The relays function more reliably in cold temperatures (but it turns out you need a transistor to drive the relays anyways), but you need more current to switch them (and the normally open relay sucks power to keep the switch closed if it that matters in the grand scheme of things).

And then there is the issue of how to make the receiver and circuit rugged and withstand -36C temperatures. I think this is the biggest problem.
 
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Remote 12 volt lights

Thank you for the input, The power wires are coming from the battery in the truck. If it was not going to be too diffucult to keep the wiring in the vehicle very limited and not have to run wires throught the firewall. Is there a possible way that If I run a keyed ignition wire out to the plow along with my power wires from the truck that through a relay I could power up the lights on just low beam and not worry about high beam lights?
 
Sorry, I didn't quite understand your last sentence. I also missed the low-beam/high-beam part, but I don't know how headlamps switch between high beam and low-beam.

I'll assume this is what you mean to say:
Thank you for the input, The power wires are coming from the battery in the truck. If it was not going to be too diffucult, [I would like] to keep the wiring in the vehicle very limited and not have to run wires throught the firewall. Is [it possible to] run a keyed ignition wire out to the plow along with my power wires from the truck [and use] a relay [to] power up the lights on just low beam and not worry about high beam lights?

I am not sure how a keyed ignition wire works. Is it a wire that passes some current when you turn the car on? Is it just a pulse when the car is turned on? Or is it continuous? If it's continuous and you use a regular normally open relay it's not a problem. If it is a pulse you would need to use a two-way latched relay. BUT if there is no pulse when the truck is turned off you have no way to wire the relay to turn off the lights when the car turns off. I think the way you wired it up would decide whether it was high beam or low beam so yeah that's probably possible.

I assume that when the whole thing is running, the lights on your car are supposed to be off while the lights on the plow are supposed to be on? If you don't mind both of them being on maybe you could just splice off a wire from the headlamps to power the relay for the plow lights (or, if the wires can carry enough current you might be able to just plug splice plow light cable straight into the regular headlamps wires).
 
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Bulldog makes a remote door lock kit. $45.00 It turns on a relay to inhibit the starter. I used the normally open terminal to do exactly what you want. They also make a remote engine start kit.
 
dlawn, do you already have the remote control system? I've been installing alarms, remote engine starters, and all sorts of various systems exactly like what you are in need of for years. Let me know what equipment you have, if any, and I can write up a diagram for you.

For instance. With a typical keyless entry transmitter/receiver you will have a starter disable output (like ClydeCrashKop stated above) which is basically a ground output when the system is "armed". You could use that output to turn the lights on/off easily. For the high and low switch it would be easy if the remote had 2 auxiliary outputs, use one for high and the other for low. Most remotes have 1 or 2 aux outputs and are usually momentary outputs. It's simple to make any relay a latching type with a diode but it will only turn on and stay on with a pulsed input. To turn it off you'd need to interupt the power to the relay momentarily. The 2nd aux. output from the remote could do that through a relay. Some remote systems have outputs that are programmable to either be momentary pulsed outputs or latching until you press the button again. This would certainly be the model to find if you don't already have the parts.
 
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