Tea Light Enhanced with ATtiny85

LED tea lights can enhance the mood at your dinner table, poolside, or anywhere else you need a little light, without the danger and hassle of an open flame. After purchasing a set of these faux candles, Roger Bühler thought the flickering wasn’t as natural as he would expect. Instead of accepting this situation, he modified the candle’s circuitry to accommodate an ATtiny85 for control, and thus his own custom programming.

Bühler documented the mod on GitHub, including code and a how-to guide. Modifications consist of first taking apart the screws on the baseplate, then desoldering the main IC and clipping the LED’s positive lead. Two points on the board are also connected so that the LED is properly earth grounded.

An IC socket/perfboard is prepared for the ATtiny85, and connections are made to the main board for power, ground, and a PWM LED output. There’s also a connection for the candle’s IR input to the ATtiny, allowing the set's included IR remote to still be used.

The ATtiny85 has to be programmed externally. This isn’t included directly in the writeup, but it references this page if you want to use an Arduino Uno for the job. The result of this hack is LED lights that can still be charged via the stock charging station, and last for up to 15 hours. They look entirely stock on the outside after this mod, and can now be programmed to behave any way you like!