Re: Controlling Holiday Lights

["Max" <nospam@xxxxxxxxxxx>]

I assumed he was talking about some device other than a triac that could be
switched
at a much higher frequency on and off during any point in the ctcle.   I
imagine this
 would work to give you some lesser power out.  All you would be doing is
chopping
the AC into really small chunks and they would average over the entire
wave(s).
 I think the problem would be noise and heat.


"Marc_F_Hult" <MFHult@xxxxxxxxxxxxxxxxxxxxx> wrote in message
news:kurmk2dodtre59igl26b3rtf82jlkpmgok@xxxxxxxxxx
> Not to worry ;-)
>
> A TRIAC controlling 60hz AC can only be switched on (it turns _itself_
> off) at
> a maximum rate of 120 hz no matter what the input. So regardless of the
> frequency of the input, and regardless of the waveform, there will be a
> maximum number of 120 transitions per second. (IOW, what sylvan is trying
> to
> do does not actually work.)
>
> The maximum output slew rate (and potential noise) occurs when the AC
> waveform
> is at 90 and 270 degrees (= peak voltage of 170 volts, rms output voltage
> for
> the entire half cycle = 85Vrms, and ~33% output for typical tungsten lamp
> compared to full output). These calculations assume 120VAC and neglect the
> band-gap and IR drop (loss owing to resistance) of about 1-1/2 volts.
>
> See http://www.econtrol.org/dimmers/TRIACDimmerCalcs_MFHult.pdf
>
> ... Marc
> Marc_F_Hult
> www.EControl.org
>
>
> On Thu, 02 Nov 2006 23:30:07 GMT, "Max" <nospam@xxxxxxxxxxx> wrote in
> message
> <3cv2h.78624$E67.37158@clgrps13>:
>
>>If I am understanding what you are trying to accomplish I would
>>have two possible concerns, 1) What kind of noise would be
>>generated by switching that fast and 2) what kind of heat would
>>be generated by having your control device switching on and off
>>that much?
>>
>>