Low side switching is not an option unfortunately. Are the N-fets a solution to the transistor voltage drop?

Also, do you think we should be looking for a replacement for the LM317 for future designs?

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.

hi, thanks for the early reply.

the relevant output is j6 which is connectect to six red lasers with separate positive terminals and a common ground to power them independently using the pwm function of arduino. They should be a mostly resistive load but they have quite high parassitic capacitance. We can’t have separate grounds and switch low side since the external casing of the lasers is connected to the negative terminal of the laser diode and it is bolted to the same aluminum frame. The lm317 is working as a constant current driver and we found online that it’s best to switch Vi instead of ADJ in this case link. Is it possible to use the circuit in the first schematic of the link to solve this? We are currently dropping .7V between base and emitter of the transistors.

Could otherwise placing the switching transistor after the cc driver be a solution?

The circuit seems to work perfectly with a lower voltage laser diode and doesn’t seem to have problems with transients. Also thanks, will try to simulate it in spice!

Pleas guys, learn from the Brigate Rosse. Put him in a f*cking trunk (use a chrysler pt cruiser for the occasion please) and goodnight.

Thanks everyone for the answers, that’s really good news! I will try to plant some other edible things in my garden too now!

Thanks for the detailed explanation, not the answer I hoped for but definitely the answer I needed! Will look into all 3 options, thanks again!

First of all thank you for your answer! What I meant with animation is the light color modulation itself, so I would basically need to listen to incoming driver data and record it to play it afterwards as an animation (yes, we would export to usdz in order to import in reality composer).