This is the board that I used for this article. ATtiny45 from Atmel, programmed to fade three leds in sequence. I decided to use a microcontroller so I could explore different patterns to see what works and what doesn't. I realize that microcontroller might not be an option to all so I decided to see if I could find another way to make the lights dance.
4017 Decade Counter
I used this circuit in my Animated Lights project back in 2001. The version on the left lights up one led at the time with the speed controlled by the 555 timer chip. Replace the 47 kilo-ohm resistor with a potentiometer and you have an adjustable speed controller.
Circuit on the right is bit better for our current use. It is basically the same but the output pins have been buffered with NPN-transistors. This makes it possible to drive more leds and with higher current. Notice the blue wire going from the pin 7. to pin 15. Pin 15. in 4017 decade counter is the reset pin and by hooking it up with an output pin, resets the chip to the first led in the sequence automatically. This way one can decide how many different acrylic layers to light up. This works for three layers but move the wire to pin 10. and add a transistor to pin 7. and you now have a four stage light show.
Originally I built this circuit to control a RGB-led. One of the latest uses includes a heat sensitive faucet add-on. Video of the prototype in Youtube.
It was pretty easy to alter the program to fade the leds with software PWM. The chip is running with an internal resonator at 8 MHz and this is plenty for three separate channels. The trimmer pot is used to alter the effect speed.
I could have used the simple light-one-layer-at-the-time but I decided to see if I could come up with something better. As the logo is built from three separate "objects", the two lines of text and the ring around them, I decided to light them up in stages but keep them all lit for a moment and fade them all out at once. This gave a lot more interesting effect as you will soon see.
All wired up and ready. I was quite surprised how thick and heavy the final results were. 9 mm in total. Next the end result with the lights on.
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