How do I limit the current to 150ma from 350 ma . Or can I run 2 strings of leds off this ?
To limit the current to 150mA, you need to change resistor R7 from 1 ohm to 2.33 ohm.
can you tell me purpose c4 68pf and is the size critical for correct opperation of the the circuit ?
It determines switching frequency and it is critical.