[sdiy] audio controlled light show

[Theo]

SSR are triacs? didn't know that.

The dimmer packs I've used all brutally cut off part of the sine wave.
I worked for about 3 years as a theater technician, 3 days a week, unpaid,
talk about time consuming hobbies ;)
The work was actually more building up the stage and setting the lamps then
anything else.

Anyway, everybody always said the packs used triacs, but I never opened one
up to see myself.
If I understood correctly, the trick is to wait after the zero crossing
before switching the triad on, then it stayed on till the next zero
crossing.
Sounded rather simple.
If triads can't do the trick it probably where close relatives (discs?)
called by the wrong name.

And yes the packs needed solid emir suppression, but usually didn't have it!
or at least not solid enough.
Putting the packs away from all other equipment, and keeping all audio
cables far as possible from the light cables was the workable solution.
Due to the high power (2000 to 4000W per channel) the packs where already on
separate AC groups.
Even stuck in a far away closed, you can hear those dimmers work!

Cheers,
Theo


From: harry <harrybissell at prodigy.net>

> Most SSR ARE Triacs, or inverse / parallel SCRs... with a built in
> optoisolated zerp voltage switching circuit.  They cannot be used for
> dimming except by dropping cycles, which will flicker the lamps badly.
>
> Real phase controlled dimmers need some SOLID EMI suppression
> to make them sort of electrically benign...
>
> H^) harry
>
> Theo wrote:
>
> > Most dimmer packs for theater use triacs to switch the lamps.
> > Probably a lot cheaper than using (solid-state) relays.
> >
> > There was a circuit for a "theater" dimmer pack in Elektor a while back
> > (sorry don't have the issue handy)
> > For the intended theater use it was a bit on the flimsy side, only
> > 500W/channel or so.
> > But for a audio disco show this Elektor circuit might give you all
> > inspiration you need ;)
> >
> > Maybe try a search for "dimmer pack circuits" or something like that.
> > There are bound to be lots of examples on the web.
> >
> > Hope this helps,
> > Theo
> >
> > From: Brett, Bill <BJB at dolby.com>
> >
> > > Greetings,
> > > I am building a light controller that responds to an audio input. I
have
> > > figured out how I will do the audio signal to logic part of the
circuit.
> > > Question... how do I turn on/off the 120 AC for the lights. I thought
of
> > > using relays, but this will produce a slight lag between audio beat
and
> > > light pulse. Of course this lag will be added to the lag of the light
> > > powering up. Maybe this lag is insignificant? Does anyone now of a
> > schematic
> > > that uses solid state to do this?
> > > Thanks
> > > -Bill
> > >
>