Where to mount backup lights?

VortecJeep

VortecJeep

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Aug 24, 2005
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Concord, NC
I bought a cheap set of LED lights to mount somewhere on the back of tow rig to help in hooking up the trailer and backing it at night.
So where have you mounted backup lights?
The ones I bought are not flush mount.
 
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Similar to ^ but just outboard of the hitch and inline. The hitch then provides protection
 
I would go with the obvious mounting places.

But I would also get a 3 way relay or whatever you call it to wire it in with the reverse lights but also have them on a switch so you could turn them on without the truck in reverse.
 
77GreenMachine said:
I would go with the obvious mounting places.

But I would also get a 3 way relay or whatever you call it to wire it in with the reverse lights but also have them on a switch so you could turn them on without the truck in reverse.
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You could also use any general purpose relay and a few diodes. You can use as many inputs as you can dream up if you use diodes..
 
Fabrik8 said:
You could also use any general purpose relay and a few diodes. You can use as many inputs as you can dream up if you use diodes..
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S'plain lucy....I failed EE200 and generally hate dealing with electrical components. But I'd love to have more control of lightning on my rigs
 
CasterTroy said:
S'plain lucy....I failed EE200 and generally hate dealing with electrical components. But I'd love to have more control of lightning on my rigs
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Wire a switch to a diode to a relay to turn on lights.

Tie a wire into the 12v + side of reverse lights to diode to same side of relay as manual switch.

Think of Diodes as check valves that only let electricity flow one way.

You don't want reverse light to energize manual switch, and you don't want manual switch to turn on reverse lights.
 
CasterTroy said:
S'plain lucy....I failed EE200 and generally hate dealing with electrical components. But I'd love to have more control of lightning on my rigs
Click to expand...

So diodes let current flow in one direction only, which is why the electrical symbol looks like an arrow pointing to a bar. Current flows in the direction of the arrow.
So if you use a few diodes, all with their outputs connected to the relay, a voltage signal forward through any one of those diodes can turn the relay coil on, but that signal can not flow backwards into any of the other diodes. So all the signals are isolated from each other, and it also doesn't matter if more than one signal is present because they'll both flow to the relay coil without affecting the other signal.

You're doing what's called "diode logic" because you can make some crude intelligence by directing the sign flow and where things are connected. In this case, with a bunch of signals going to the relay, you're making a logical OR gate with multiple inputs.

The one minor thing to watch is that diodes have a voltage drop across them, which is just a characteristic of how they work as a semiconductor. It varies with the type of diode, but let's say it's 0.5V for example. So your signal to the relay coil is whatever your signal voltage is minus that 0.5V, which is really no big deal unless your signal is already getting into the marginal voltage range to switch the relay if you have a dying battery or whatever. The voltage drop isn't really related to current flow like something resistive, its pretty fixed regardless of current.

If you're going shopping for diodes, Schottky diodes are the lowest voltage drop, and have a high enough voltage rating for 12v use (but not many other things, which is the problem with Schottky diodes) as 50v Schottkys are pretty common.

I used to design automotive electronics so I tend to go a little overkill on voltage drop, min voltage ratings, widest possible input voltage range, etc. A simple cheap rectifier diode will work just fine for switching a nice simple relay..
 
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