Re: I think they've done it again.

[nobody@xxxxxxxxxxxx (Dave Houston)]

The reports of flickering go back at least a year. At that time someone with
Smarthome said it was caused by defective triacs. Now, someone from
Smarthome is saying it is caused by a choke.

To kick Jeff's idea around a bit. The Insteon signal starts 800µS before ZC
which is approximately 10% of the time it takes for 1/2 cycle. I'm not sure
of the maximum amplitude of the Insteon signal. The specs give a minimum
figure (3.16Vpp). On my scope it appears to be about 3Vpp (but that may be
distorted by the ACT ScopeTest-2 I was using). If it's symmetrical about 0V
this means the negative peak is about 1.5V. I haven't done the trig but the
point where the line voltage drops below 1.5V is awfully close to ZC. While
the Insteon signal might cause a premature turn-off, I really doubt that
anyone would perceive a flicker. It would just increase the off time
slightly. The lamp would turn on again at the point past the ZC called for
by the dim setting. I don't know how the Insteon electronics detect ZC but
doubt whether a 1.5V amplitude would be detected.

If non-Insteon devices are being affected by such a low amplitude signal so
near ZC (I've seen reports of Lutrom dimmers and Leviton X-10 dimmers
flickering when Insteon signals are being sent) it would seem they would
also react to triac noise from other dimmers which is much higher in
amplitude. Even if their triacs are turning off in reaction to a false ZC,
they would (by Jeff's reasoning) turn on either at the normal point or turn
on and off at twice the Insteon 131.65kHz rate.

I think it takes some rather large voltage anomolies that last for more than
1/2 cycle to cause a perceptible flicker and don't think the Insteon control
signal fits the bill (of indictment).

"Jeff Volp" <JeffVolp@xxxxxxx> wrote:

>Since Insteon starts sending data BEFORE the actual zero crossing, I suspect
>that dimmers using the zero crossing as a time reference may be confused by
>the Insteon signal.  That would cause the triac phase to be modulated by how
>early that erroneous zero crossing is detected.  At full intensity, the
>triac should be triggered right after the real zero crossing.  If the
>Insteon signal causes the triac to be turned on early, it would switch off
>at the real zero crossing, and miss conduction for the next half cycle.
>Similarly, dimmed lights would change intensity in response to any shifting
>trigger phase delay.
>
>Since X10 sends its data after the zero crossing, dimmers that use zero
>crossing as a time reference would be unaffected by X10 data.
>
>There are reports of dimmers made by other manufacturers being effected, so
>this may be a nasty problem to resolve.
>
>Jeff
>
>"Dave Houston" <nobody@xxxxxxxxxxxx> wrote in message
>news:4496d9fc.206904843@xxxxxxxxxxxxxxxx
>> As for trying to reconcile the reports, that's what I was alluding to when
>I
>> said some reports may be due to user inexperience or ineptitude. However,
>> there have been reports from someone who is neither inexperienced nor
>inept
>> that some X-10 dimmers are flickering during Insteon events. I think the
>> most likely culprit is excessive triac noise getting to the mains from the
>> Insteon dimmers. That could also explain the Lutron dimmer report.
>>
>> It really seems improbable that Insteon, X-10 & Lutron devices would all
>> flicker in some reaction to the low level Insteon control signals.
>>
>> Also, I'm not really losing confidence in Insteon. I still think the
>concept
>> is sound. I think the problem is one of too much haste in introducing new
>> devices and maybe cost cutting in component choices. The demand has been
>> high for new devices
>