A simple multiplexed RGB LED array controlled with hardware SPI from an Arduino Pro Mini. Each pulse from a Geiger sensor produces a 32-bit random number that sets the color of one RGB LED site.
<p>The first part of the video shows the "lamp test" sequence. Before the Arduino sketch begins running the LEDs show a static pattern, then the sketch blinks each LED site in succession, fills the entire array with random colors, and begins executing the main loop that changes one LED at a time.
</p><p>The rapid count comes from a radium-illuminated wristwatch near the Geiger sensor that produces about 160 count/minute. The last minute shows the 12 count/minute background rate.
</p><p>More info on my blog, starting at:
</p>
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