What is it?

A pair of rechargeable LED earrings, powered by a hybrid super capacitor (LIC). The super capacitor is surrounded by 12 red and 12 blue micro LED's (1x1mm). The capacitor management and LED patterns are controlled by an ATtiny1616.

Why did you make it?

For years I have been looking for an environmental friendlier solution to power the LED wearables. I tried several super capacitors before, but these were always too big and not able to power the wearable for a couple of hours. So instead, I used coin cell batteries, and I just made sure that these would last as long as possible. But wasting coin cell batteries was not my only concern. Every year little children ingest these batteries resulting in serious injuries. Fortunately, a new bill passed (Reese’s Law) which will put stricter requirements on using coin cell batteries which will hopefully result in less accidents. After reading about this new law, I decided to look into super capacitors again, and I found these fairly new hybrid super capacitors (LIC). These are a combination of Lithium batteries and super capacitors, but unlike batteries, hybrid supercapacitors do not degrade with each charge/discharge cycle and are much safer than batteries, since there is no risk of thermal runaway.

What makes it special?

This might be the first LED wearable that is using hybrid super capacitors (LIC). To maintain the longevity of the super capacitor the voltage must be kept within 2.5V - 3.8V at all times. The wearable has a redundant charging system that primary turns off the charger at 3.8V, and secondary limits the voltage to 4.0V max. The micro-controller will put the wearable in sleep mode when the voltage drops below 2.8V.

Charging the wearable takes 3 minutes. The LED's will provide charging progress during charging. After all the LED's turn blue the wearable is charged for 90%. The red LED indicator on the back of the wearable will turn off after the wearable is fully charged.

Super capacitor is rechargeable up to 500,000 cycles, which should be enough for the rest of your life and generations to come ;) The USB charging port will probably wear out before that.

The patterns of the lights can be changed with the push button on the back by selecting one of the following modes:

• SINGLE_CW
• SINGLE_CCW
• SINGLE_BOTH
• SINGLE_SPLIT
• DOUBLE_CW
• DOUBLE_SPLIT
• DOUBLE_CCW
• TRIPLE_CW
• TRIPLE_CCW
• ALL_SOLID
• ALL_MIX
• DEMO

The single CW and CCW modes can keep the wearable powered up to 30 hours, while the all_solid and all_mix can leave the LED's on for about 10 hours.

Note: The push button on the wearable is locked during shipping to make sure that the LED's are not turned on accidentally. In order to unluck the pushbutton an USB type C charging cable is required. Just plug the charging cable into the wearable and a charger, and the wearable will be ready for use.