This deluxe solar-powered light uses a battery and solar cells salvaged from a solar lamp with a four-cell battery (4.8 V nominal terminal voltage).
The circuit can operate from any DC voltage around this value and its current consumption, at 20 mA, is low. This means that the battery can give up to five days of operation. The circuit consists of an Atmel ATtiny microcontroller which drives a red, a green and a blue LED directly from three port pins. Series resistors are of course included to limit the LED current. The microcontroller drives the LEDs in sequence to produce an RGB running light effect. The microcontroller is also responsible for ensuring that the light automatically switches on when it gets dark and off when it is light. The light sensor is made from one of the solar cells from a bro-ken solar lamp (it is more common for the battery to fail rather than the solar cells).
