Somebody call?? [Linked Image]

Well, NJ has pretty much covered it already, but I'll add my 2 cents.

Yes, these sorts of switch-mode power supplies really are almost everywhere these days. TVs were one of the first domestic appliances to adopt them during the 1970s, although they've been around longer than that in commercial applications. These days you'll find them in VCRs, computers, and even in the charger units for some cordless tools.

The economics have played a big part in consumer goods. Transistors and ICs (integrated circuits) are dirt-cheap to manufacture now, whereas traditional transformers for 50 or 60Hz are relatively expensive. The switch-mode supply just needs a cheap, lightweight transformer which usually has a ferrite core due to the high operating frequency.

The combination of price, size, and weight is what has made them so popular in today's miniature equipment.

In the application of LV lighting, there's no particular advantage in using the higher frequency for the bulbs. It's purely the cost/size/weight factor over using a taditional 60Hz xfmr to feed them.

I agree with NJ on the interference question on the "el-cheapo" units. I've seen some here with harmonics and other hash right up into shortwave frequencies. Terrible.