"Adam Aglionby" wrote in message
...

Pulse width modultaion, subject of several U.S. patents in relation to
LED dimming but thats a rant for another time, 555 as suggested can do
it, fly swimming slowly in ointment is V drop, only have 3V to play
with , drop 0.7V across a semi junction, even low Rds Fet will drop a
bit.

At which point maybe the resistor may be as efficient, depending on current.