joeforker posted his ATtiny LED driver for an RC car in the project log forum:
I thought I’d share a little board I’m making to add headlights to a model car. The board is a little 1″ square thing with mounting holes. The top right contains a constant-current driver built from a BC847 BJT, a 2N7002 MOSFET and a current set resistor “the Instructables circuit”, “Power LED’s – simplest light with constant-current circuit”. I hope to have overkill-bright headlights by passing 100-200mA through these devices; hope they don’t get too hot. I’ve added a trimpot to be able to reuse the board as an adjustable current source and, rather than tie the MOSFET gate to +, it’s tied to a pin on an ATtiny. The micro will be able to switch the light on and off based on a signal from the receiver (the left header). The bottom of the board contains a LDO and a JST-XH header that will connect directly to the balance plug of the car’s 2S LiPo battery.
Via the forum.