Mushroom LED Keyring
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Building an LED mushroom keyring
A short build video showing the green and yellow LED mushroom circuit being soldered and fitted to a keyring.
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About
Green and yellow LEDs laid out as a mushroom cap on a mini solderable breadboard, running off two CR2032 coin cells in series with a slide switch for on/off. The LEDs go two in series behind a single 1kΩ resistor, and those six pairs sit in parallel across the rails, so they all light together and a dead LED only takes its own pair out. Designed in Tinkercad first, then soldered up and fitted to a keyring, with the parts coming to £3.80. It doesn't look much like a typical mushroom, but it turns out there is a green-capped, yellow-stemmed one out there - Leotia viscosa, the Jelly Babies mushroom.
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