Re: Water heater eating X-10 signal

[lnh <lnoh@xxxxxxxxxxxx>]

In article <463877f0.83255828@xxxxxxxxxxxxx>,
 nobody@xxxxxxxxxxxx (Dave Houston) wrote:

> lnh <lnoh@xxxxxxxxxxxx> wrote:
>
> >> Appendix C, FIGURE C-3 (within dashed line rectangle)...
> >>
> >>      http://ww1.microchip.com/downloads/en/AppNotes/00236a.pdf
> >
> >Off to the parts house. Thanks.
>
> While there, grab a 25VAC wall transformer if you're interested in recording
> lengthy sequences with a soundcard. It will provide isolation while getting
> the line voltage down to a level that's safe for humanoids before devising a
> circuit to make the 60Kz and 120kHz levels safe for the soundcard.
>
> Alternately, you can open up your ESM1 and use it as the source for input to
> a soundcard. John Galvin reverse engineered a schematic for the ESM1 shortly
> after it was introduced.
>
>      http://home.pacbell.net/lgalvin/esm1.gif
>
> This is so obvious that I should have thought of it years ago as the need
> for lengthy PLC captures arises frequently. (In my defense, I usually use my
> DSO 'scope.) Recording them as .WAV files allows for editing and analysis in
> a Wave editor (e.g. Goldwave) with the length only limited by disk space.
> Tapping into the ESM1 really simplifies things. You can get 60Hz on PIC pin
> 13 and the signal on PIC pin 18, it's isolated and all low voltage. If I
> were ELK, I'd add a 1/8" stereo jack and a few resistors and double the
> price. ;)

Interesting. I would have thought the wall wart would attenuate the high
frequencies we were looking for.

By the way, I built the scope circuit in the AppNote above. It seems to
work, although I won't be able to test it until tomorrow. I also built
in the 32KHz high pass from the AppNote to play with.

Thanks again to all.