Hi guys!
This circuit is simple yet powers up 1-5W IR LEDs with constant current. Any idea to make a pulsed LED driver?

 

Hi guys!
This circuit is simple yet powers up 1-5W IR LEDs with constant current. Any idea to make a pulsed LED driver?

Just pull the gate of the FET to ground with another small transistor.

 

If you want to use it as pwm control then you can using a 555 pwm, and the output connect to the (+) of U2 LM358.

 

Thanks!

 

Hi guys!
This circuit is simple yet powers up 1-5W IR LEDs with constant current. Any idea to make a pulsed LED driver?

What is the wattage of each of the resistors shown in your drawing

 

For Figs. 2-3-4, I used a 1Ohm 2W resistor as R3. Rest were 0.25W.
For the 0.33 Ohm resistor in Fig. 1, I don't remember the Wattage. It was about 3cm long ceramic resistor.

 

Just pull the gate of the FET to ground with another small transistor.

With the op-amp versions, a resistor could be inserted between the inverting input and the current sensing resistor, that would allow an added transistor to pull the inverting input high - sending the op-amp output low.