Help, please! Problem with 9mm diode build

Jstrawn said:

I'm using an adjustable test load set to 4 diodes, is that right?

Click to expand...

No. Your 1ohm is dropping 2.4V (Georg Simon Ohm says it's the law!). Adding another 0.9*4 brings up the total load voltage to 6V. Blue diodes run closer to 4.5 I think. Running 2 diodes at 2.4A or 3 diodes at 1.8A will more closely match the voltage of your laser diode.

Cyparagon said:

No. Your 1ohm is dropping 2.4V (Georg Simon Ohm says it's the law!). Adding another 0.9*4 brings up the total load voltage to 6V. Blue diodes run closer to 4.5 I think. Running 2 diodes at 2.4A or 3 diodes at 1.8A will more closely match the voltage of your laser diode.

Click to expand...

Yes, please do this. If you have a second multimeter you can measure the forward voltage as well as the current output so you can get as close as possible to the correct load. I just tested a driver with 4 diodes@2.4A, and like yours it lasted a bit before failing completely. These drivers can't take that kind of load...you can keep the money I refunded you, as I thought I posted this earlier (must have hit cancel on accident), but please test the other one this way before it dies too.

Oh shoot, would that really kill the driver? If so, that's my fault and I will gladly pay you back.

Man that's dumb...

I will test it again though

Okay, I tested both drivers with two and three diodes, and I was not able find any detectable difference. The output was fine at low setting, but would drop again on higher settings. Neither are dead, but they do not go to full current. One of them never did (although maybe it just failed too quickly?) And the other one did, but it didn't fail until after setting the current, only when I hooked it up to the actual diode. Which makes no sense because it handled the test load fine but couldn't do the 4.5 volts? This one still goes up higher with the test load but fails with the diode above around 1.8A as DTR noticed. I tried with about 2.1 amp setting on the LD and it lased for about fifteen seconds before stopping. Then bring it down to 1.8A it has been fine so far.

Crazyspaz, did your driver die completely after 4 diode test?

It had a weird failure running 2.4A@4 or 5 diodes (dont recall which :/). Pretty sure the IC just died, because I was seeing some weird output.