Wagner Lipnharski wrote:
> Jan-erik Soderholm (QAC) wrote:
>
>>Wagner Lipnharski wrote:
>>[about only switching TRACS'at the zero crossing pont]
>>
>>Sounds interesting !
>>Just a minor point...
>>
>>Take this setting as an example :
>>
>>
>>>Cycles ON   Cycles OFF    % Power  Status
>>>---------   ----------    -------  ------
>>>   5          4             55       m
>>
>>Here, we have a "blink" frequency of 1 / (9 * 0.20) =
>>aprox 5.5 Hz. Now, I don't know if this is visible,
>>but, as having a son with epilepsy, I know the *some* people
>>are very sensistive to flickering lights, even those
>>not *visible* to us "others".
<snip>
> I agree with you, but there is a difference in response time from a CRT and
> an incandescent lamp.
> The CRT phosphor should react very fast, well, at least for our eyes, its
> "persistance" should be enough to allow the trace to scan all the image and
> get back, I guess it is no more than 1/20 of a second.  The persistance of
> a incandescent lamp is a little bit higher, I guess more than 1/2 of a
> second, mostly for lamps 100W or more.

Some theatrical dimmers use "dimmer doubling" where they control the
half cycles independently. The output from the dimmer is fed to two
lamps with a diode in series with each arranged so that one lamp gets
the +ve cycles and one gets the -ve cycles. The system uses 77V lamps
instead of 120V. (US based) The dimmer desk has two faders for each
dimmer output. From what I've heard, the lamps don't seem to suffer
from flicker but then again, they're higher wattage than usual being
in the range of 500W - 1000W usually.
David...

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads