Hello everyone, We have a problem with a circuit we built. The circuit seems to work properly with a green laser diode (130mA, lower voltage). With the red laser (higher voltage) on the other hand, the circuit delivers only 60mA max of the 130mA it should be giving the laser.
The problem seems to be the transistor's resistance because it works properly if we bypass the transitor and give +5V to the LM317.
Is it this assumption correct?
We tried a few transistors (BC241, BC236, TIP41C and TIP41) but with no luck. Is there a way to find a drop-in replacement for the transistor? MOSFET seem to have lower resistance but require an external driver with Arduino.
We need to use the Arduino PWM with these drivers, so at least 980hz switching frequency is needed.
Thanks in advance
Thanks. J5 is 6 parallel jumpers to probe and adjust the current via RV[1-6]. J6 is connected to the laser diodes. As explained in another answer, we unfortunately must use a common ground.