I already built a constant current source (using a NPN BJT, a N-MOSFET and some resistors, 30mA) that drives a red laser diode (I bought it from ebay for 1$). I also placed a N-Mosfet switch that disconnects the whole circuit from the GND. So I can on and off the Laser output in high frequency (I m gonna measure it and post it).
My problem is that after some minutes the Laser output brightness decreases.
Does anybody have the experiense on laser diodes driving to help me understand and solve the problem?
Also is there any Laser Diode driver ic ?
Thank you in advance.