An RGB LED Ring Using an ATmega168
When I first saw this LED ring, the first thing that came into my mind is a Christmas tree entirely covered by these glowing rings of awesomeness. There are two versions; the first version makes use of 3 P-channel MOSFET that cycles through the primary colors and makes use of only a single LED ring constant current source. The second version uses three separate constant current sources made from MBI5168 – this would rid us of the need to cycle through the colors and give us more brightness. The color balancing can be done in hardware – turning potentiometers in ht back of the PCBs. There is a warning when dealing with these rings – the current constant current sources and the LEDs can generate a lot of heat, sometimes too hot to touch. Also, these devices are rated to operate <=5V, it can work in lower voltages, but the LEDs would be less bright. To operate beyond the 5V, you would need to use a regulator to avoid popping your chips. Continue reading
