Solar pocket light

A fast and easy, project build for fun. A solar cell charges a single micro NiMH battery. A step-up converter provides 4V. The ATtiny13 powers a red, green, blue and ultraviolet LED. Normal operation of the button is to toggle the red, green and blue LEDs on and off. If pressed longer, there can be switched between each possible combination of LEDs being on. Material bill is approx 18€. Low battery warning is done by flashing the LEDs, oh and there is a disco mode too. Because the reset pin is used as I/O pin, a HV programmer might be required.


Software and schematics

As always, use at your own risk. Software and schematics version 1.0
solarPocketV1.pdf Just the schematics

Charging per day

Out of curiosity, the charging performance of the solarcell was measured. The cell (30mm x 30mm, 3V, 35mA) laid flat behind a window, directing to the south. There were some cloudy days and some with clear view.
Day Charged
11.03.2016 6.9mAh
12.03.2016 2.7mAh
13.03.2016 10mAh
14.03.2016 15mAh
15.03.2016 3.1mAh
16.03.2016 9.6mAh
17.03.2016 16.4mAh
Total 63.6mAh