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pedro[_3_]

On Fri, 13 Dec 2013 19:17:04 GMT, (Andy
Wood) wrote:

"Bob Milutinovic" wrote:

It's an air-cored transformer in its simplest form, with absolutely no
"smarts" in the base unit - meaning you'll have 50Hz emanating from the
base.

Interesting...

I always assumed that things like that did just drive a coil at the
mains frequency, and I was a bit surprised to discover that was not
the case for a couple of torch/nightlight combinations we have. I did
not bother to try to trace out the circuit, but it comprises bridge
rectifier, capacitor, a high-voltage transistor and not much else that
I can remember besides the coil.

A coil placed nearby one of those sniffs out a 23kHz signal.

Interesting indeed. I have one of those combo devices here in bits
and did trace out the circuit. One greencap-type cap had blown its
guts and a resistor across it was cremated. Lacking values - and I
suspect these *may* alter the oscillator frequency - it remains it
bits. That 23kHz info may help reolve it.

These toothbrushes are obviously different. I wonder what make them go
down the one path vs the other?

The Braun certainly has an amount of electronics in it - see the video
here on replacing the battery in a 3738.

http://www.youtube.com/watch?v=um3ncK4FonM