AC/DC topics (the current, not the band)

[curtis73]

A wee bit off the straight and narrow (I always am)

I'm considering purchasing a vintage aluminum "twinkie" camper to restore and I'm thinking way too far ahead. One of them has no ceiling panels and it reveals some really neat aluminum roof stringers. I had the idea of roofing that segment with translucent plastic and lighting it with some of that cable-strung low voltage lighting from IKEA (gosh I love that place.)

I have a lot of that lighting in my apartment, and I tested the transformers. They are all 12v output, but still 60Hz AC. If I were to wire this stuff in to the trailer's 12v DC supply, (bypassing the transformer obviously) would there be any issues since its just a light bulb? I know there won't be any electrical problems, but will my 10w light bulb now be operating differently now that the electrons are only going one way?

The trailer will most likely be stationary and always hooked up to 120v, so I could run it with the transformer, but why do that if I don't have to, right?

[li_gangyi]

Probably the lamp will have shorter life when operated in DC......I've seen some bulbs with some "derating" graph according to different frequencies....wonder if I can find them now....

Edit...Ok here's the data...
1. Common filament bulbs (lamps) will perform to their life specs when operated at 50HzStablised AC.
2. Ambient temperature is in the range of 20deg C to 25deg C.
3. No mechanical vibration is present.

Deviation from this standards can have significant effects on lamp life, particularly with low current filaments (<80mA)
Operation from a DC supply at rated volatge can reduce specified life by up to 50%.
The following effects of variation from rated operating voltages should be noted:
5% above will reduce life by up to 50%
% below will significantly increase lamp life (didn't specifiy how much)
Current consumption can vary up to +/-10% on stated values at the rated supply voltage. Care should be excersiced when running a series of lamps in series. In such applications it is reccommended that the rated volatage of lamps be reduced by 10% to prevent premature failure of individual lamps.

[dhaen]

But make sure the cable thickness is good enough, and that each line is fused Watch out for cable chaffing due to vibration and movement.
I think that even with sensible cable, there'll be enough voltage drop for there to be no more than 12v on the bulbs themselves.
As for the DC thing... well, your car headlamps last long enough, don't they?

[curtis73]

Great ideas. I'm going to use rubber grommets in screw eyes to run the cable and I'll supply it with some heavy-ish gauge wire. There will be about five 10w bulbs, so fifty watts at a (lets be cautious) 10v supply is 5 amps. I'll probably run it with 10 ga wire to be overkill

The cable itself is about 6 ga steel cable covered in a clear silicone sheath. You hang the wire with included screw eyes and hooks, and it clamps on to turnbuckles to tighten it. Then you run the remaining slack line to the transformers (which I think I can omit) Then you attach the light fixtures to the cable with clamps that pierce the insulation and provide juice to the bulbs. Its a neat setup.

Thanks all for the info.