Re: I think they've done it again

[Marc_F_Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx>]

On Wed, 2 Aug 2006 19:11:41 -0400, "Robert Green"
<ROBERT_GREEN1963@xxxxxxxxx> wrote in message
<LsSdncGTk8msr0zZnZ2dnUVZ_t-dnZ2d@xxxxxxx>:

>"Dave Houston" <nobody@xxxxxxxxxxxx> wrote in message
>news:44d0f843.1326363906@xxxxxxxxxxxxxxxx
>> The author of those posts received one of the new "fixed" dimmers and
>>he seems to confirm what I wrote here in his post dated 08/01/2006 :
>>1:35:2PM
>> where he says the SmartHome "fix" is a much larger choke that merely
>>masks the underlying flaw.

Trouble is, he doesn't know what he is talking about as evinced by this
conclusion, by his bewilderment as to why INSTEON dimmer uses a TRIAC with
a logic level gate, and his statement that 'I sure learned a lot about
TRIACS'  (or some such).

TRIACS used in dimmers can be triggered into conduction either through the
gate _or_ the output.  The flickering is caused by the latter not the
former.

An R-C snubber or inductor is virtually *always* used on the output, not
to cover an "underlying flaw" as is stated here, but by design, and on
purpose and out of necessity.

That is not to say that there may not have been a shift in parameters of
the TRIAC ( I don't know), either by substitution, mistake, or
manufacturing tolerances, or some other cause. Only to state that the
notion that using a larger inductor to prevent retriggering is entirely
conventional and customary  and is not covering up an "underlying flaw" as
is asserted here by the neophyte as parroted by Dave Houston.

As a coda,  it may be useful to note that another retrofit that would both
fix the flicker problem and reduce RF and other noise proliferation (US
standards on noise emissions are less stringent than European) is to
simply add an external choke as previously mentioned.  I note with a
chuckle that the chokes alone on many DMX dimmers weigh as much as 4 or 5
entire INSTEON or [name any <600 watt residential dimmer here).  No
flicker. Greatly reduced RF radiation. No filament sing. And so on. But it
takes up volume and costs more. So what else is new? Design tradeoffs and
hiccups in rev. 1.0 production. Welcome to the real world.

... Marc
Marc_F_Hult
www.ECOntrol.org