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question about hooking up multi-color LED

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question about hooking up multi-color LED

Old 11-02-04, 12:19 AM
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question about hooking up multi-color LED

Hey all, I've just bought a light "bulb" that has a color changing LED inside. Before buying it, I thought/hoped that it would have multiple LEDs that would slowly cycle through the color spectrum

After buying it I realized that it's alctually only a single LED that cylcles through the color spectrum (red, blue, aqua, green, purple etc) but it does it in a really annoying way. First at a medium speed, then a slower speed and then flashing through each color in a strobe-like fashion... and then it repeats the cycle.

Since this isn't the 'effect' I was hoping for, I'd like to try and figure out how to change the pattern to just a slow color-cycle.

BUT, I don't even know how this single-led works. There are color-changing led lights that work off a small microprocessor, but that is NOT the case with this item. I've also read about 2-color leds that have three leads to them which determine which color will light. That is NOT the case with this item. It only has 2 leads. Elsewhere on the net I've been led to believe that it's possibly a voltage variance that causes the colors to shift.

SO (after all of that) I'm looking for some "tech" advice. Does anybody know how these multi-color-led-lamps work? Any thoughts on how I can get it to stick to one 'slow-change' mode? Any electronic studs around here?
Thanks
Old 11-04-04, 12:27 AM
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Here's a general schematic of how the LED is wired up. I put this together but I really don't know what it means. Anybody out there who can tell me what's going on in this circuit?
Thanks

Old 11-04-04, 12:36 AM
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I don't know anything about those types of LEDs but your circuit just appears to supply a DC current to two leads and doesn't pulse or vary the voltage/current/signal going to the LED at all.
Old 11-04-04, 01:10 AM
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I guess one of the things that confuses me is the fact that both the + and - are 'combined' and go to one of the LED leads while just the - goes to the other of the LED leads

The other thing that confuses me is why there are all these things wired in parallel

As the power comes out of the "bridge rectifier" (which converts the AC to DC if I'm understanding this correctly) and then goes into the LED, the "-" side is not only connected to the "+" side but it also goes to a diode, a capacitor and a resistor.

And it doesn't go to the diode, capacitor and resistor in series, going from one thing to the next, but in parallel, going to all three simultaneously and then coming out the other side, being re-connected again before attaching to the LED.
Old 11-04-04, 03:56 AM
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The capacitor going across the bridge's DC output leads is to ensure stable DC output to the LED. It's like a filter for the power. You always see these when using a bridge rectifier in an LED circuit.

The diode and resistor in parallel with the cap... them I'm not sure about. The resistor is just going to draw power and get hot, realistically. Only reason I can think of is to prevent the capacitor from surging at the initial startup by limiting the amount of current it can draw. The diode might be along the same lines.

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