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About 25 years ago a friend of mine found a schematic in an electronics hobby magazine for a color organ and he built one from that plan set. About 20 years ago he grew tired of it and gave it to me to play with. I eventually gave it away to another friend.
Then, a few years ago I started wondering if it might be possible to find the original schematic on the internet - no kiddin'; there it was! Included with it was a newer version.
Starting from that original scan of the "newer" schematic I redrew it in this version. Let me explain why my version is different from the original by first explaning what a color organ is.
A color organ is a circuit that uses bandpass filters to split up an audio signal into 2 or more signals that will trigger colored lights, hence the name "color organ". There are devices which will trigger a strobe in time with music and they are sometimes sold as "color organs", but they are not really. The output signals in this case consist of 4 pairs of X-mas tree lights of 4 colors, blue, green, red & yellow. The lowest frequencies in the music will trigger the string of blue lights. The lower medium triggers the green string. The upper medium triggers the red and the high freq drives the yellow lights. So the brightness of the lights that flash corresponds to the frquency of the music. Bass-heavy music will fill the room with blue light and a screaming Stratocaster will fire the yellow lights. A stobe that only responds to rhythm does not do that.
The original plan was monaural; it had only one input for the speaker wire. All I did was duplicate the circuit so that there would be two of everything, from input to light triggers, but only one power supply. Modern power supplies are better than the ones we worked with in the past and the other components are more reliable, so I'm sure that the duplication of the circuit will not be a problem.
Still, the version that my friend built had all the heat=generating components, expecially the SCR's, mounted on a huge heat-sink. The other significant difference between the old and new is that this new circuit includes an IC while the one my friend built used a series of transistors.
I haven't had a chance to build this version yet, so I can't tell you it won't blow up.
If you have trouble reading the text then copy/paste to your own hardrive and it should be easier to read. If you want to discuss it you can email me at redscott77092{at}yahoo{dot}com
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