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From: Gary Tait
Subject: Re: Audio controlled decoration
X-Newsreader: Forte Free Agent 1.92/32.572
Date: Tue, 17 Dec 2002 14:27:13 -0500
NNTP-Posting-Date: Tue, 17 Dec 2002 14:28:31 EST
Organization: WorldCom Canada Ltd. News Reader Service
On 17 Dec 2002 04:34:16 -0000, Steve W.EE
>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.
Try the Ramsey (or similar) schematic with
triacs instead, or supply the lights/SCRs through a full wave bridge
(no filter though) instead of directly from the AC line.
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