# How To: Cycle through 3 LEDs, One at a time

Discussion in 'Homework Help' started by jfeldstein, Jul 19, 2011.

1. ### jfeldstein Thread Starter New Member

Jul 19, 2011
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Hi all.

Looking for a circuit that will let me cycle through 3 LED's, or the three colors of one RGB LED very quickly, one at a time.

Something like this first circuit, but faster and for 3 LED's instead of 2.

I'd like something that doesn't use an IC, ideally. I'm afraid that the chips will be too big to fit into the space in which I want to use them. (Inside a broomstick =^p) A simple circuit also seems easier to power.

Thanks for any tips!

~Jordan

Apr 24, 2011
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3. ### jfeldstein Thread Starter New Member

Jul 19, 2011
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Being non-microcontroller based was just because I've only used Arduino and the chips are pretty big.

Something that small would certainly work, but I am in over my head in some of this: I don't know what an "App" is, was expecting to see some kind of circuit diagram and don't know how I feel about "software solutions," which I keep reading about. I'm pretty sure the logic for what I want is very simple, I'm more concerned about how to build the dang thing.

Thanks for the post.

Jul 9, 2011
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5. ### jfeldstein Thread Starter New Member

Jul 19, 2011
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This is exactly what I was looking for. Not sure if it works either =^P

Going to learn how to read these circuit diagrams, and give it a shot.

Thanks!

Oh, before I forget: Is this something I could run off a couple of AA batteries?

Apr 30, 2011
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You're going to need at least 5V for the blue LED, transistor junction and resistor drop (≈3.8V + ≈0.7V + ?). I'm no fan of 9V batteries but this would be a good place for one. In my simulation of Bowden's circuit (link below) I used 68µF capacitors and a 9V supply. It transitioned between colors at about 0.8Hz. The dropping resistors for the LEDs need to be around 390Ω (different for each LED).

Last edited: Jul 20, 2011

Mar 24, 2008
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8. ### thevoodoochild New Member

Jan 14, 2011
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A tiny pic chip is not big & can adjust speed with sw.

9. ### M Haris Khan New Member

Jul 20, 2011
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May be you can use a single IC (which contains counter+decoder) set counter to count 0 1 2 0 1 2 0 1 2 ( other IC may be for clock). other wise you need multiple caps, R, transistors. may be single or two ICs will give more compact sol.

I like PIC sol also it is also available as flat quad package v v compact but u need PCB for using it.