Hi All,

Is there any way I can use the 12V lighting on our trailers from both a 12V and a 24V vehicle?

I've got an application at work where I need several trailers to be interchangable between several vehicles which have varying supplies. I believe I've reard of some electronic gadget from an OZ company called REDARC which does such a thing but i've been unable to get much info as to how it works.

Does anyone know of such a unit or another solution that can be sourced here in the UK?

The trailers all have lighting built in and i'd rather not mess about with temporary lighting boards for the 24V vehicles.

Any ideas?

Cheers,

Lee

You would need to fit some gadget to throw out 12 V over the trailer socket for 24 V vehicle.

The way I would do it is to use an ocicallor that is swtiching at 50 % duity cycle i.e. you get 24 V square wave that will average out to 12 V (similar to what the series LR voltage regulator does) - and a capactior to do some smoothing - not 100% sure that would work due to voltagae spikes (so need a bit more thought).

You can get 12 V voltage regulators but your trialer lamps are typically 21 W to that is about 2 A,

you would need quite a few of these, indicaor, side lamps, rear lamps and stop but should be doable for under a tenner per vehicle.

(or fit the eqivallent bulb in series in the trialer socket wiring on the prine mover - wasteful but simplest)

Well the cheat option would be to add 20 diodes to the ground return on the 24v sockets = 12v dropped

The sexercisey version would be some sort of voltage regulator but anything that will handle the current will be expensive.

I'd make up a short extension cable for the 24v vehicles with a load of diodes tucked in a plug so you can run 24v, 24->12v or 12v.

Why not just have 2 trailer boards, they are very cheap... one for 12v and one for 24v, or is that too simple?

Not cheap but this might be what you are after.

Chris

You also get power supplies for CB's etc which run a 12v appliance from 24v. You could leave this attached to the trailer - they just regulate down to 12v, so will still spit out 12v with a 12v vehicle. Then you can plug in to either, risk free!

24 to 12v converter
This one is about £12 - Mind you, you would need four of them.
One for each indicator, one for stop and one for tail lights.

Last option, go to RS or Maplin & buy a load of 7812 voltage regulators these will convert pretty much any voltage up to 30v to 12v. Put one in each bulb holder. 7812's chan be got for a few pence!

Easy to wire up. They have three legs. Looking at the side with the printing, the left one goes to the 24v feed, the middle to earth and the right to our 12v bulb. The three legs go quite nicely in a small connector block.


Si

That looks a bit cheaper. Could you run just one on the earth return cable?

Chris

You're not wrong. However, you'd have to guarantee the cable is the only earth return - i.e. the light fittings do not warth to the trailer chassis.

Also, each 7812 is good for about 1A. Even though the indicators draw about 2A, they are only on half the time so 1A average. You can conect as many as you like in parallel though.

Si

Hi Chaps thanks for the replies! some excellent suggestions.

Chris, that's exactly the kind of gizmo i was looking for. £100 isn't that much - since the company will be paying! and looks like it does exactly what it says on the tin!

If it were a personal project where i would have to foot the bill then i'd have gone for one of the build it yourself solutions and saved a few quid.

Cheers all,

Lee.