John Payson wrote:

> Personally, I'm just hoping someone will produce a small wall-dimple (smaller
> than a wall-wart) with an unregulated 100KHz oscillator driving a small
> transformer.  I think such a thing should be produceable cheaper than normal
> wall warts (the cost of the electronics should be offset by the use of a
> smaller transformer) but I have not seen this done; the only similar thing
> I've heard about was one which produced a regulated output (and cost an arm
> and a leg); I would think that an unregulated output could be much much chea-
> per.

"They" already have invented such a device. The company is Power
Integrations, Inc. They have a range of three-terminal off-line PWM
switching regulators. Most of them are in TO-220 packages. I'm not
sure how much your arms and legs are worth, but I was quoted "very
reasonable" prices for the PWR-TOP204YAI. (Very reasonable means that
I don't remember the price, but it was cheap enough for me to include
it in a design.)

Their phone number is (or at least used to be): (415) 960-3572.

Scott