Re: I think they've done it again.

[Marc F Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx>]

On Sat, 24 Jun 2006 09:58:52 -0400, "Robert Green"
<ROBERT_GREEN1963@xxxxxxxxx> wrote in message
<4OadnWBVub0A2ADZnZ2dnUVZ_vmdnZ2d@xxxxxxx>:


>
>I just hope someone takes some photos of the modules before Insteon swaps
>the troublesome units so we can know for sure what's been changed.

The TRIAC snubber circuitry typically consists in an resistor-capacitor (RC)
network but is sometimes an inductor ("choke").  Most dimmers using these
semiconductors do have output chokes to reduce the noise. Architectural
grade dimmers often have chokes 100 times larger than residential dimmers.

All three models of INSTEON wall dimmers I have looked at have output
inductors. In general, series inductors decrease the rate of voltage change
(dv/dt) but _increase_ the magnitude and time duration of line transients
caused by TRIAC or back-to-back SCR's.

Choke inductance and saturation current depend on the geometry and
composition of the core as well as wire gauge and number of turns. The size
and number of turns is easy to inspect/verify, but the inductor core
composition is not. So if an off-spec core was used by a fabricator, it
might not be detected until the dimmers started to cause problems in
marginal situations.

FWIW, I've encountered no noise or flicker problems with INSTEON (n = ~16),
but my large loads are controlled by a dimmer panel in the basement with
donut-sized filters/inductors. One of the several benefits of switching from
X10 WS467 to INSTEON ICON dimmers has been to eliminate the buzz in my main
audio system caused by a nearby X10 dimmer.

... Marc
Marc_F_Hult
www.ECOntrol.org