On 2006-11-16, John Fields wrote:

Perhaps three flip-flops?

Doing it with one switch is really easy with a counter. (press and A
lights, press again, B lights, press again, C lights, and over again).

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Not only is that not what he asked for, it won't work properly since
the first time he pushes the switch "A" will light, then the second
time "B" will light, then the third time "A" and "B" will both be
lit, and the fourth time "C" will light. Pressing the switch again
will start the cycle anew.

Johnson counter ?

Anyway it could be done with a dual flip-flop and a few diodes
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LED A goes from Q1 to Q2
LED B from Q1 to ground
LED C from Q2 to ground.

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Bye.
Jasen