Re: X-10 Broadcast Storm Detector

["Robert Green" <ROBERT_GREEN1963@xxxxxxxxx>]

"Dave Houston" <nobody@xxxxxxxxxxxx> wrote in message
news:46df23d5.1113339265@xxxxxxxxxxxxxxxx
> "Robert Green" <ROBERT_GREEN1963@xxxxxxxxx> wrote:
>
> >All of the various power supplies I've assembled from the junk bin have
> >quite a variety of non-standard connectors.  I am going to chop them off
and
> >wire them all to a 4 pole, 6 position rotary switch (still new in the bag
> >from when Lafayette went belly up and they were selling stuff like that 5
> >for a dollar!) that will feed into the ESM1 head.  Then I'll set up a
nearby
> >TM751 on an unused housecode and use a big spring clip to lock a PalmPad
> >into continuous send.  We'll see what the signal looks like as I step
> >through the different wall warts.  Any ideas how I can attenuate the
signal
> >from the stronger transformers so that they can be calibrated to give
close
> >to the same readings?
>
> Wait to see whether you can see any difference.

So far, I've just tried two transformers.  One that puts out 11VAC at 1.2VA
and another that puts out 13.5VAC at 12VA.  The 11VAC unit causes all the
bars on the ESM1 to light up but they never extinguish.  Until I tried that
I hadn't noticed that even the stock PS causes what appears to a be a
boot-up sequence in which all the LEDs flash briefly.

The second transformer, a hefty beastie that once powered a heated massage
cushion, produced results that were basically similar to the stock power
supply.  It's hard to make precise estimates because the bars tend to
flicker a bit.  The unloaded voltage for the stock PS is about 13.5VAC.  I
have a power supply that's marked 13.5VAC and actually reads about 16VAC,
but I am reluctant to test it on something that provides a higher voltage
than the stock transformer because it might cause the magic smoke to escape!

The next test will be to see if 100' of 16 gauge speaker wire will attenuate
the signal, and if so, how much.  If I can still get adequate signal with
that much wire, I'm going to consider the multiple transformer phase of the
testing complete, since you've established other transformers work as well.
I'll then move on to selecting the components and creating the circuit
design to read the ESM1 LEDs via phototransistors and sound an alarm if the
meter head detects an X-10 type signal for more than 30 seconds.  I don't
care if it's noise or valid X-10 commands because anything that "blows a 10"
on the ESM1 meter is capable of obliterating valid X-10 commands on the
line.

I'd like to create a circuit that's able to differentiate between noise and
valid X-10 signals, if only for troubleshooting the source of the broadcast
storm.  That should be pretty simple.  All I need to do is to check whether
the "X-10 Good" LED lights up along with the segments of the bar graph.  I
think it would be a good idea to monitor the very first segment of the LED
bargraph, too, because lately I've been seeing the first segment light up
and stay lit when the basement shoplites are running.  I might decide to
have the audio alert play a different tone if the background noise level
goes beyond that first segment.

It looks as if the LEDs are close enough to the surface of the meter display
window for me to be able to read them without spillover, but I won't know
until I actually start trying to read the pulses whether that's going to be
an issue.  I think the best thing to use to butt up against the EMS1 display
would be an 1/8" thick piece of black rubber with holes drilled in it to
precisely line up with display LEDS.  That should be easy to do.  I'll take
a piece of tracing paper and place it over the display head so I can mark
the positions and then take that paper, tape it over the rubber strip that
I'll tack to a piece of thin wood and then I'll drill holes through the
paper, rubber and wood.  The thin strip of wood will be thick enough to hold
the phototransistors securely in place.  I can bend the leads at a right
angle and mount the circuit board horizontally in the plastic box that forms
the mating part of the cradle.

FWIW, I tried to induce reading errors by moving the ESM1 head all around
the wall wart.  I had remarkably consistent readings.  I did notice that the
parallax error arising from the clear plastic lens and bargraph interface
could easily lead someone to believe they were seeing one less bar when
viewing the device from an angle.  That parallax error means I may have to
shroud the phototransistors carefully to insure they read just the LED
they're aimed at. I hope it won't come to removing the clear plastic lens
from the front of the meter to assure a tight optical coupling, but it could
come to that.

Next thing to do is get some phototransistors and see what sort of output I
can get from a flickering LED and then how to turn that output into a a
multipoint audio alarm.

--
Bobby G.