lots of whirly LED domes

birdsong not included …

For it-seemed-like-a-good-idea-at-the-time reasons, I’ve ended up with a couple of tubes of the big dome LEDs. A tube is a lot; something over 20 pieces. Oh well, I’ll find uses for them eventually.

It seems these are LEDTronics 806 Series ‘Super Intensity 20mm Big Dome 6-Chip LEDs’. The datasheet shows they are configured as a DIP-12, with LED cathodes and anodes alternating around the pins:

Dome LED pinout: 12 pins, spaced 15.24 mm across, 2.54 mm between pins
that’s a pretty big dome

The six LEDs are enough to use all of the available PWM pins on a regular Arduino. The green LEDs I have look like they’re supposed to take a current-limiting resistor of ≥ 75 Ω or so at 5 V. The 100 Ω resistors I used did pretty much max out the weedy regulator on the cheap Arduino Nano I was using, so you may want to use bigger resistors if you want to avoid having your USB disappear.

No Fritzing model of the part yet, but here’s a sketch that works, but quite fails to use any interesting PWM functions at all:

// do a whirly thing with the 6 LEDs inside a LEDTronics L806T_UG-LIME 20 mm Big Dome unit
// scruss - 2020-04
// https://www.ledtronics.com/Products/ProductsDetails.aspx?WP=281
// each thru 100R resistor - which might be rather small

#define MAXPINS 5
int pwmpins[] = { 3, 5, 6, 9, 10, 11 };
int i = 0;

void setup() {
  // pwm pins as output, all initially off
  for (i = 0; i <= MAXPINS; i++) {
    pinMode(pwmpins[i], OUTPUT);
    analogWrite(pwmpins[i], 0);

void loop() {
  if (i > MAXPINS) {
    i = 0;
  analogWrite(pwmpins[i], 255);
  analogWrite((i > 0) ? pwmpins[i - 1] : pwmpins[MAXPINS], 0);

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