4-6 LED Color Changing Platform

Well, you could try a fader circuit driving two different colored LEDs out of phase to get various colors of the combination of the two.

Something like shown at the link. Replace the incadescent lamps with LEDs and a resistor.

eh, there's got to be something cheaper, i like your thinking but i want more than two colors and it seems like i should be able to build something like this for under a couple of dollars. building this circuit for each light would get expensive, four 555's four 2n3055. Besides, i'm looking for something small and portable, a twelve volt battery would either die to quickly or be to big and heavy, and if i lowered the voltage i would have to change the resistor and capacitor values which i don't know how to do. Thanks for the idea anyways, it was a good one.

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There are 'mood leds' that just do this. You only need a resistor to limit the current a bit.

Or else, a PIC of course.

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Thanks, Frank.
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All of your idea's have been good but not exactly what I'm looking for, last night I was trying to come up with a circuit that would do what I wanted it to. I have the principle down but not the knowledge. I was thinking of using high storage capacitors connected in parralell with an LED and in series with a resistor to slow charging time to about two seconds, causing a red LED to phase in. Once the red LED reached full brightness I would use a yet to be determined circuit to phase in a yellow LED as the red one dimmed. Then once the yellow LED reached full brightness I would use the yet to be determined circuit fade in a blue LED as yellow faded out. Then it would shift from blue to red. If I can get this circuit to work it should shift through the full color spectrum at a relaxing four seconds. Any body got any good ideas?

It doesn't use any 555s. It's the circuit below that called "automatic 12 volt lamp dimmer" It uses one LM324 (quad op-amp), a few resistors and

2 small transistors. Probably costs less than $2 and produces 3 colors from 2 LEDs. If you can work out a 90 degree phase shift from one of the outputs, you can drive another 2 LEDs and they will all be separated 90 degrees.

-Bill

To make all colors, you want a red, a green and a blue led. Red and green make yellow.

You want to adjust the current through each to change the intensity.

To make this smooth needs quite some circuitry. However, changing the intensity of each one independently would be an option. Or use a constant current source and some drive mechanism to favor two of the 3 leds - the constant current will keep intensity constant but it will cycle through all mixes including white and white tints.

Thomas

Sounds like those mood leds are my best option

Commercial products of this sort use a micro PWMing three LEDs (or a tricolor RGB LED, which is nothing more than three LEDs in one body). The LED is the most expensive part of the circuit.

You can build this for probably under $1.00, not counting the LED at home, use an Atmel ATTiny11 micro ($0.54), three series current-limiting resistors, and three 'AAA' cells.

A tricolor LED is going to be expensive though, e.g. Digi-Key

67-1829-ND is $7.26. Using individual LEDs will be cheaper but the blue LED is going to set you back a bit of cash.