To: <topband@contesting.com>
>Date: Wed, 04 Dec 1996 14:08:20 -0800
>From: Garry Shapiro <ni6t@scruznet.com>
>
>Eric:
>
Snip...
>Eric Gustafson wrote:
>
>>
>> 5. If it is a dimmer, the maximum noise amplitude coincides with "device
>> off" state. Minimum noise coincides with "maximum brightness" state.
>>
>
>However, I partly disagree with you on this point. Although there could
>be dimmers out there whose "off" position is not really off but near the
>triac conduction threshold, I have usually noted maximum radiation
>emission partway between minimum dimming and full brightness.
Gary,
You are absolutely correct about the normal pot controlled dimmers.
However, in the above statement I was specifically referring to _touch_
controlled dimmers. The touch control circuitry for these dimmers is the
culprit in the "off but still powered" state. For some reason even the
touch controller source is somewhat reduced when the load is receiving full
power. But when the load is unpowered, the touch controlled dimmers either
produce more noise or radiate it more effeciently than at any other
setting. The touch controller is also the source of the 20 KHz patches
of noise spaced every 200 KHz. The ordinary dimmers don't have this
characteristic. They are simply wideband noise sources.
Thanks for the good information on a source for (relatively) quiet
dimmers. I won't allow any dimmer in my house that can't be turned off
with an integral mechanical switch. At least I can silence those without
pulling the plug.
73, Eric N7CL
--
FAQ on WWW: http://www.contesting.com/topband.html
Submissions: topband@contesting.com
Administrative requests: topband-REQUEST@contesting.com
Sponsored by Akorn Access, Inc & KM9P
|