Car dome light rigged for under-cabinet application?

[RaysnCayne]

Hey guys,

I have a cabinet in my shed that casts a small but vicious shadow over my work bench. So naturally, I'd like to fix that with an under-cabinet light. I do have an old 2' fluorescent fixture I could rig up. But it's really heavy and I feel I'm already taxing the cabinet's payload with all the junk I put in it.

I came across this little car interior dome light in my parts box awhile back. I'm no electrician so I jabbed the wires into and outlet and of course POP! went the bulbs.

So I figure I need some sort of transformer (or resistor?) to make it work. Does anyone have an idea of where I could source such a unit (and a small one) for cheap or free? Like out of an old TV or something? I'd rather not have to go to Radio Shack and spend $25 on something if I can just pull it out of some junk I may in my attic.

Creative and thrifty ideas welcome!

 

[pattenp]

Cars are 12V and House is 120V. You need a transformer to run the 12V light. Just go buy a cheap 120V under cabinet mount lamp.

http://www.lowes.com/pd_240195-207-FA201HBL_0__?productId=3125493&Ntt=fluorescent+lighting

 

[malibu101]

Cars are 12V and House is 120V. You need a transformer to run the 12V light. Just go buy a cheap 120V under cabinet mount lamp.

BUT cars are 12 VDC as opposed to the house which is 120 VAC.

Do bulbs care if they get AC instead of DC?

 

[RaysnCayne]

Just go buy a cheap 120V under cabinet mount lamp.

On the first reply no less. Where's the fun in that? I said creative and thrifty ideas.

This is Garage Journal, not Practical Consumer Journal.

 

[pattenp]

On the first reply no less. Where's the fun in that? I said creative and thrifty ideas.

This is Garage Journal, not Practical Consumer Journal.

Well salvage a 12V wall wart from something to power the light. You need one that will have enough amps for the bulb.

 

[pattenp]

BUT cars are 12 VDC as opposed to the house which is 120 VAC.

Do bulbs care if they get AC instead of DC?

I think a 12V incandescent bulb works on either. I haven't really thought about it.

 

[Jeff Ivers]

Do you have any Malibu outdoor lighting? Their transformers put out 12 volts - run a wire to your fixture and you're done.

 

[Vinci]

Well salvage a 12V wall wart from something to power the light. You need one that will have enough amps for the bulb.

This will work. I am guessing that a dome light is probably around 15 watts, so you'll be wanting a wall wart that will give you 1 amp (1000ma) or better. That would be the cheapest way to go.

If you want to spend a little money, you can either find a cheapie fluorescent fixture or check out the LED strip lights available on Amazon. I suspect that either option would run you around $15.

 

[tylernt]

DC incandescent bulbs don't care if they're run on AC. They'll be slightly dimmer on AC (probably not noticeable by the human eye).

I'd be cautious with incandescent bulbs in close proximity with a wooden cabinet. You might want some kind of metal heat shield when you mount them as they will get pretty toasty after being on for an hour or more.

The double-ended cylinder dome lights are sometimes called "festoon" bulbs. To cut down on heat, and allow you to run a whole bunch of festoons on one little AC-DC power supply, LED festoon bulbs are available.

 

[gayler]

How about an old computer power supply? While your at it you could hook up your old 8-track player and listen to some toons!

 

[KPSquared]

You should just keel stuffing wires in outlets until sonething works.

 

[Charles (in GA)]

I too appreciate ingenuity, but sometimes, creating a fire hazard, and taking the long way around the globe to solve a problem, is simply not the best way. You will end up with wires, and splices, that are not in enclosures and it will look just like what it is, a kludged up mess.

What is wrong with the old light you have? a 2ft fluorescent light cannot weigh over a couple of pounds, even with a heavy magnetic ballast. If the cabinets are that flimsy you probably need to do some remodeling in the garage anyhow, before it falls off the wall onto you some day.

Beyond that, the small self contained under cabinet T5 fixtures are not that expensive, and work nice and look neat.

Charles

 

[gatchel]

I think a 12V incandescent bulb works on either. I haven't really thought about it.

I can confirm this. I have used several of those 12vac hockey puck under cabinet lights in 12vdc applications. I've used them mainly in trailers and other vehicle work spaces with success and no abnormal failures.

 

[Larwyn]

If you have the transformer (old wall wart etc.) laying around and the dome light fixture there is no real reason not to use them if you want. Regardless of how cheaply you can buy a "proper" 120 volt AC light the cost is 100% more than using what you already have. A 100% price difference is generally considered to be significant in my world....

 

[RaysnCayne]

Howdy guys,

I actually got it all installed and wired the same evening I first posted this query. But glitches with it have had me scratchin' my head ever since.

A friend of mine gave me a nice laptop charger (it's rather old so he's not sure what it was) that looked like it was going to work perfectly. As you can see in the pics, I wired in a switch and hooked it all together.

The first few times I flipped the switch, it seemed to work fine. But then it took some jiggling at the dome light connections to make it come on. So I took it down and sanded all the contacts. Now it only works if I pull one of the spade connectors off the dome light fixture and then plug it back in. If I leave the spade plugged in, the little green transformer light (see dot beside the mounting bracket) won't come on and thus not send current to the dome light. But if I leave the connector unplugged, the transformer light will come on (I have to plug the spade in to get the dome light on).

So I guess it's something with this transformer. I know all the wiring's good. But it seems like the thing needs some sort of "jolt" to activate the transformer. Anyone here know what the deal with the transformer might be?

I'm about ready to throw in the towel and admit I should've used my 2' fluorescent fixture or bought a new one.

 

[tylernt]

Laptop power supplies are "smart" with little computer chips inside to control them. They expect to be plugged into a smart laptop and negotiate power loads. Since you have no laptop, the brain in your power supply is confused.

 

[RaysnCayne]

That's what I was suspecting. Thanks for confirming. There's something about that transformer that needs "feedback" before it activates. Oh well. It's what I had on-hand and thus far, the entire set up has been free.

I may rummage through the attic and see if there's anything worth pirating. If not, I'll give up and go be a consumer.

 

[tylernt]

That's what I was suspecting. Thanks for confirming. There's something about that transformer

Actually... I believe you will find that it's not a transformer, but a SMPS (Switch-Mode Power Supply). It'll have a small inductor coil in it, but it's not a dual-winding transformer.

If you can find something with a huge heavy dual-winding transformer, then that should do the trick.

 

[sberry]

I am all for rigging but finding a 120V fixture here is the most practical. I would rig a 2 tube in there it would be super bright for task work.