... with an operational amplifier. This is a simple circuit for pulse with modulation using a 2 in a chip opamp. For description of the left part of this circuit see the circuit "Clock generator ..." of my "... with an operational amplifier." circuit series.
+ also never gets broken if you use a mosfet when you have more leds (mine works since 5.2013)
+ very simple and easy to understand
+ frequency limit only depends on the used opamp
+ supply voltage independent
- i havn't found any - until now
