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Is there and IC that splits input voltages to 8 or 10 output voltages in sequence? Answered

Not sure if that was the right way to ask the question. But, heres what I what I want to do:

Using a 9V battey. I would like to light 8, 10, or perhaps more LEDs, not simultaneously but one by one in a sequence. And in asking that, I was going to use a 555 to turn that input signal into a square wave, then perhaps an integrator to make that squarewave spike then dim out.

What I am trying to make is a "jar of fireflies" for my daughter. I would build the above circut, maybe two in the same house. So that each LED flares, dims over a moment, goes out, then the next LED starts in sequence.

So, is there a IC that does something like that. And secondly, would an integrator (R-C-Ground) work with that DC supply?

Thanks in advance for you help and advice.

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AndyGadget

Best Answer 7 years ago

I've got an idea for this in a single chip running off 9V but too late at night to work it through into a circuit now. I'll reveal the answer tomorrow #;¬)

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AndyGadgetAndyGadget

Answer 7 years ago

Sorry, I'm not going to get a chance to do this. I was thinking of an LM3914 in dot mode, driven from a the RC slope of a UJT relaxation oscillator.
The LM3914 gives 10 LEDs (with no series resistor wiring required) and fades in and out as you ask.  It's also expandable for as many as you like by chaining them.
 

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steveastrouk

7 years ago

Can't think of an IC that'd do that off the shelf, but you could do it with a binary counter and a decoder.

Make magazine showed a firefly project based on PIC micros I think.

Steve

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Asmodean_7steveastrouk

Answer 7 years ago

Thanks for the heads up on the Make magazine setup. I took a look at it, but thought twice about it b/c MC programming probably would be a little too much of an investment for me to build such a simple thing. (would have to get the programmer, etc.) But tell me what you think of this if you would, would this work for the flashing? And what about the dimming effect, would an integrator work? Thanks again for the help.

https://www.instructables.com/id/Fireflies---Analog-version.../

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steveastroukAsmodean_7

Answer 7 years ago

Thing is you need to make a ramp generator with an offset built in so the chip doesn't stop working.

You could TRY and make a 555 ramp generator, and try floating the chip on top of a 3V zener diode. Then apply that to pin 16 of the 4026. This means that the ground reference for all the parts of your generator would be 3V higher than "real" ground.

Steve