Re: Water heater eating X-10 signal

[ddl@danlan.*com (Dan Lanciani)]

In article <ivLVh.58763$VU4.23318@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>, JeffVolp@xxxxxxx (Jeff Volp) writes:

| Since the transformerless power supply cannot provide that much energy, I
| don't think the output impedance is in the fractional ohm region.

I was considering the impedance of the driver separately from the supply
characteristics.  That wouldn't be a nice thing to do in an advertisement,
but for our purposes it allows an easy measurement.  There doesn't appear
to be anything special about ACT's reactive power supply and it should be
possible to see it slump in the presense of heavy 240V loads if that is
indeed an issue.

| I thought we were discussing summing of in-phase X10 signals on the neutral
| reducing the end-point signal strength.  That would only be true if there
| were multiple X10 loads (or signal suckers) on both legs of that circuit.

I should perhaps have chosen my words more carefully, e.g.:  any
load with impedance (at the X10 carrier frequency) too low to ignore.
Multiple loads per leg are not required.  In the case of a single load
on the opposing leg with in-phase drive that load hurts you; in the
case of out-of-phase drive it helps you.  Repeat as needed for additional
loads.  To the extent that the loads approach balance with an out-of-phase
drive the impedance of the neutral between the supply and the first load
(possibly along with other segments) drops out of the picture.  In the
best case this is like getting a free 50% reduction in cable length.

This may or may not be a material effect in the real world; however,
given that the analogous effect for power transmission is viewed as
significant and given that the relative loss at X10 carrier frequencies
is considerably greater I'm not willing to dismiss it out of hand.

				Dan Lanciani
				ddl@danlan.*com