Path: utzoo!utgpu!watserv1!watmath!att!att!rutgers!sun-barr!newstop!exodus!oobleck.Eng.Sun.COM!bender
From: bender@oobleck.Eng.Sun.COM (Michael Bender)
Newsgroups: sci.electronics
Subject: Re: Dec 90 Radio-Elec "Christmas Card" article
Message-ID: <2078@exodus.Eng.Sun.COM>
Date: 5 Nov 90 08:26:35 GMT
References: <1990Nov2.142454.10784@msuinfo.cl.msu.edu> <1972@exodus.Eng.Sun.COM> <1990Nov3.024908.18792@nntp-server.caltech.edu>
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In article <1990Nov3.024908.18792@nntp-server.caltech.edu> kimf@nntp-server.caltech.edu (Kim Dorian Flowers) writes:
>bender@oobleck.Eng.Sun.COM (Michael Bender) writes:
>
>>Back in 1978 I connected my home-built "sound-light" (a term my friends and
>>I used to impress our other high-school friends!), which was a 3-channel
>>color organ, to our family's Christmas tree and played some Christmas music
>>through it (and the stereo).  I thought it was really neat.  When my parents
>>got home from shopping, they told me to unplug it and wire the tree back to
>>the way it was (no blinking lights or anything).  Oh, well, I guess they just
>>weren't ready for the onslaught of technology in the home at that time.
>
>What's the basic concept behind your "typical" color organ? The general
>intensity of sound over several different frequency ranges?

In my setup (and that seemes to be true for most of the other designs that
I've seen), I used 3 channels - the incoming audio signal would be set to a
low pass filter to one channel, a band pass filter to another channel and a
high pass filter to the remaining channel.  The results of this was that one
channel of lights would respond to the low frequencies in the audio program,
one to the midrange frequencies and one channel to the high frequencies.  I
was building these devices during the late 70's when disco was king and
everyone in town wanted to added lighting effects to their parties and
dances and things.

mike

p.s. as I found out the hard way, it's very important to use an isloating
transformer between the audio inout and the rest of the circuit if you're
not using opto-isolated triacs or scr's...
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