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Date: 20 Dec 2002 15:19:32 -0000
From: Steve W.EE
Author-Address: stevew-ee nym alias net
Subject: Audio controlled decoration
I would like some ideas on how to build a circuit
to make Christmas tree lights flash to music. I
want each of 3 or 4 colors to respond to certain
sound frequencies. For example the white lights
respond to over 3000Hz and would flash when cymbals
or similar instruments are played. I tried building
one of those Ramsey kits but the filters were
horribly non-selective you could not really tell
which lights were responding to which frequencies.
There is more stuff about the Ramsey kit I don't
like. It has a small 8:500 ohm stepup transformer
3 pots, 3 real crude RC filters and 3 SCR's.
The SCR's of course will only light the bulbs to
50 percent brightness. I guess what happens is
when the filtered audio gets above 0.7 volts the
SCR triggers. The lights flash rather nervously
and the effect is not pleasing at all.
I'm not sure whether I need an AGC because the music
source I'm using is quite compressed. I do want
something which flashes the lights in a pleasing
Can anyone point me to some circuits which I could
build in a couple days with common parts. I've got
a half dozen optos and triacs left over I'd like
to use them to feed the bulbs with full-wave AC.
Steve W. stevew-ee.nym@alias@net ( interchange . and @ )
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