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Basic color organ frustrations?

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Tombrogue

New Member
Greetings everyone;

I am a general geek looking for a way to get this basic Audio to Light modulation circuit to run from straight line level from a small cd or mp3 player.

My problem is the input here requires about 2 volts from the source to trigger IC1. It generally uses a speaker output which is then calibrated at RV1.

Is there some way I can modify the input portion of this circuit to be line level friendly. Or a way to easily step up the line level voltage to work here.

The challenge of course being that I want to keep the circuit small & simple if possible. I have built one with a small audio amp but with the power supply it required it became to bulky & complex(possibly due in part to my lack of knowledge).

Any ideas?

Tombrogue
 

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tunedwolf

Well-Known Member
I don't see how you could call this particular circuit a colour organ.
The colour organs of yesteryear used a small transformer for input step-up and isolation, the signal then being passed through several adjustable filters to an output stage, which was sometimes triac based, but more often scr based.

There is no way to drive your circuit from line levels unless you add a gain stage to the input, this could be an opamp, or a transistor solution, either way of course you will require to power it.
 

Hero999

Banned
I have a circuit for a colour organ in an old Maplin magazine, I'll post it if you like providing I can find it of course.
 

Tombrogue

New Member
This circuit is currently sold as a kit from velleman & works quite well for my need except I want to use line level audio rather than a speaker output.

I built an audio amp from a kit to use at the input stage but it required 12v to run. Now my project case quadrupled in size because I have to house a small audio amp & its power supply in addition to the original circuit.

Is it possible to incorporate something to bump the line level input up to 2 or 3 volts using power from the 110v that the output load is using without adding much complexity.

I am interested in seeing other circuits of this type to see what others have done. I understand enough that I can figure basic circuits out, just have a tough time starting from scratch.

Any input is greatly appreciated.

Tombrogue
 

Analog

New Member
basically, you're asking to get something from nothing. The line level input is marginally sufficient to drive the LED, therefore giving poor trigger results. The audio amp idea is a good one, but as you said, adds bulk. If you could find and opto isolator with a smaller forward voltage drop that would be better, but most leds require larger than traditional 0.7V diode drops.
 

Hero999

Banned
If I remember rightly the maplin kit used an electret mic input. You could remove the electret mic and replace it with a small mains transformer, connect the mains primary to the audio output and the secondary to the mic input. You might need to add a small attenuator but this is easy to do using a potential divider.
 
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