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LED Rainbow Sequencer



I guess that’s what you could call it. I’d done some chaser circuits over the last few years, and thought I would try my hand at this slightly different circuit. Because there’s no “chasing” effect, I called it a sequencer (like other people did as well).
Just about every chaser circuit you look up on the web uses a 4017 decade counter (integrated circuit), but this one uses a CD4015B dual 4 bit shift register. There was a video of a chap who’d made something similar, and he gave out the circuit diagram too. So I based it around his with a few changes. Instead of running the LEDs directly off the CD4015B, I have them connected to a Toshiba ULN2803APG 8 channel darlington transistor array, which handles all their load. I read a forum discussion about using something similar for chaser circuits and thought it was a wise move.
Timing is done with the ever common 555 timer, and there’s a 100 kΩ variable resistor on the back to control the speed.
Each pair of LEDs horizontally has its own resistor to (attempt to) equalise the brightness down to the weaker purple ones I used. That’s why the white ones that make up the face are so much brighter! They’re just connected in 4 groups of 3 in series, to the 9 V power supply. There are no RGB LEDs used here; they’re all single colour ones. Red, orange, yellow, green, turquoise (just 2), ice blue, regular blue, purple and magenta.
So yep, I hope this has enough artistic merit! It took me 8 days to get it all assembled! I spent about 3 hours or so on each day, doing it. I swear people who use those surface mount components must be into self-torture! These regular ones were enough to do my eyes in. I did a grid in Corel DRAW, which I printed out to know where the LEDs would go, and put all the other components around them. I just used a prototype dot board, because this is a one off.
And if anybody’s wondering, or about to ask a tricky question, I’m not an electronics expert by any means. Just an amateur who likes to put together the odd circuit maybe twice a year. But I did start assembling kits about 30 years or so ago, so I guess I learnt a few things.
Hopefully at Christmas time, I’m going to do up an old transformer from about the 1950s and give it a shnazzy box with a rectifier, filter / reservoir capacitor, voltage regulator, a couple of meters and what not, and power this sequencer and other doodads off it.
I’m going to upload an animated GIF file to compliment this photo as well, and I’ll link it here when I do so. :-)… - this is the animation.
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© 2022 - 2024 JohnK222
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