How would I go about constructing this circuit?

Question

I want to build a circuit with three LED's: a red, a green, and a blue. The forward voltage is about 3.5 for the green and blue LED's and 2.0 for the Red. I want it to cycle through the three LED's as such: R -> RG -> G -> GB -> B -> BR -> R indefinitely. Does anyone know how to make this possible? It needs to be battery operated. THANKS!!!!!!

Answer 1

I would approach the circuit thus. Use cmos logic ICs. A 4049 buffer will provide sufficient current for LEDs (limit the current with resistors). A counter like a 4019 will provide the timing. You could use a 555 timer for the clock or use logic gates to make the clock. You specify seven states and a 4019 will provide up to ten states. use 4011 nor gates for the logic.  I made a similar circuit that runs off a 9 volt battery.

Answer 2

Sounds like a good job for a programmable microprocessor, but otherwise probably a clocked chip like a counter, 6 outputsthen reset, then diode steering to select the desired LED combinations. The battery would need to be of larger voltage than the highest LED striking voltage, with suitable value current- limiting resistors in each one's circuit, after allowing for diode and other component losses.