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A circuit for randomly lighting LED? Answered

Hi all

I am a newbie in analogue and I would like to make something for hobby.

I would like to build a circuit with breathing lighting effect for 5 to 6 LED, and they breath individually at random time, so to create some random lighting effect, and the circuit may be powered up by a 3V battery.

So how can this individual random time for switching the LED on and off done please?


I'm doing something similar in THIS Instructable. The LEDs flash randomly - Really easy to do with a Picaxe microcontroller.
The 08m chip I'm using actually has only 3 LED outputs, but the similar 20m has 8 outputs - Ideal for what you want.  The Instructable gives a fair bit of info on the Picaxe. 

thank you for your reply, it seems to need some time to understand how to program the microcontroller, so do u believer that I can use this microcontroller to create the random breathing effect on several LEDs??

By the way, I did some search outside this forum, ppl seem to use a 555 timer to do this effect, but if I follow this method, does it mean I will need 1 timer per 1 LED I have on my design please?

Use an arduino with a pseudo-random number generator subroutine. Sounds fancy and complex, but it's not. Cost you maybe $39? (someone correct me on that dollar amount) for the arduino. At a guess, the arduino either has a canned routine or one can be downloaded from someone, or, alternatively, written yourself. There are many many webpages that investigate random number generation code.

is it possible to do this task with only some analogue and possible a simple microcontroller?

Yes, you can do pseudo random generation using a a hybrid or pure analog circuit. It's just such a pain and arduinos seem to be popular here at instructables that I punted for an arduino.

AndyGadget uses a picaxe as he shows above (and he even offers up a very nice instructable, not something I'm likely to do). I'd use whatever I had my hands on be it a picaxe, an arduino, or some other microcontroller microprocessor, etc, or hybrid/analog circuit.

But detailing an analog circuit for you isn't something I'm willing to do. Too much work for too little gain. That's why I got a degree, so *I could do this sort of thing. Get a degree and you can too. Otherwise search the net or use the off-shelf hobbyist tools.

No offense intended with my comments.

I'm voting for Andy and suggesting that you use his instructable.