Transformer for 12v halogen lights

I would certainly get the proper PSU for those lights. If yours are the same as mine, the so called transformer is actually a switch mode power supply with an un-rectified output at about 200Khz.

Baron wrote in news:fonpqm$paq$ snipped-for-privacy@aioe.org:

OTOH,12V is 12V,as long as the transformer can supply the 10 or 20 watts per bulb. the bulb doesn't care if it sees 60hz or 200Khz.

It's just that the switchers are smaller,cheaper than ironcore xfmrs.

From what I've seen of the ones that I've bought for my house, sets of three tend to have a 'conventional' iron cored transformer, and sets of five have a little switching supply. Agreed with what Jim says. Any transformer will do that has the right rating. A 20 watt lamp would draw about 1.6ish amps, so that's what the transformer needs to be rated at as a minimum, for one bulb. If using a conventional transformer, don't go too much above that rating for a 12v type, as the voltage may be quite a bit higher than 12v, if the winding is loaded too lightly. This is why the makers of these lights recommend that a failed lamp is replaced at the earliest opportunity, to avoid over-running the ones that are left intact.

Arfa

"Arfa Daily" wrote in news:AEMrj.5644$ snipped-for-privacy@newsfe6-win.ntli.net:

those little quartz halogen lamps are expensive,too.

Be sure that whatever you use is thermally protected and UL approved.

Whilst I agree 100% with you Jim. The reason that I made the comment is because the bulbs are quite sensitive to voltage and the "Electronic Transformers" do provide a fairly regulated output as long as they are used within max/min loading. Mine are rated at 60W max 20W min one to three 20W bulbs.

You got good replies. I'll add that I've seen halogens run from AC with normal transformers and nothing else (50Hz), DC both linear and SMPSU, not to mention the varieties that run straight from 250VAC (in these parts). They all seem to work for their uses, more or less.

One thing to note is that you might have an innocent looking 10W bulb but when you look at it, that 10W needs nearly 1A of current and if you have a few, you'll need several amps. A common wall wart won't quite cut it.

I think the intended type SMPSU's should be relatively inexpensive and simple to wire, closed, approved, no changes needed and powerful enough for their rated loads. They might not start on too light a load, though.

SMPS efficiency should also be very good as transformers go and their switching frequency, if it causes any visible change in the light which I think is unlikely, is higher so it's less likely to cause flicker effects.