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Flashing or chasing large groups of LEDs and figuring voltages Answered

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I am playing around with making LED signs. How do I build a circuit to make a parallel string of 50-100 LEDs flash or chase? Also, when working with a large group of LEDs in parallel, how do I figure the size of DC power supply I need. Especially when there are different color requiring different voltages. On my first attempt, I used a 4.5 volt wall wart with various resistors between the white and red bulbs til I got a pretty fair brightness on both. But I was scared of frying 200 LEDs in fell swoop, so I would like to learn the proper way. I think I understand Ohms law to calculate the right voltage and amperage for 1 LED, but how does that apply to 100 or 150? Thanks!

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andy (author)2007-02-28

All I can suggest is wikipedia it until you have a good idea of what you are doing. Failing that use google. As for getting them to chase... you`ll probably require a number of microcontrolers, since its very basic you might even be able to get away with using standard ICs. Search a free schematics site for "running LEDs" and "chasing LEDs". Sorry I couldn`t be more helpful than that, best of luck!

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