pedro wrote:

.. . .

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.


The two of those that I had both came from Aldi, but about a year
apart. They had the same Aldi product code, 37737, and were both
branded Delta, but the casings were slightly different.

Like yours, one of them died. I took a peek at it, but in the end I
decided I never was going to get around to trying to revive it so I
chucked it out.

I just had a look at the other one, which is still working, and found
there is actually a bit more to it than I was remembering from my
quick look at the one that died. Circuit could be similar to your one
but maybe not exactly the same. There is a 2k resistor connected to
the emitter of the transistor, but there does not appear to be a
capacitor connected in parallel with it.


Andy Wood