Laser Starts Blinking

[Kevin520]

So I bought a BDR-209 16x 405nm laser diode with a 700ma driver attached from DTR's laser shop. I hooked the driver up to a 5 volt power supply, but after about 30 seconds it starts blinking. I imagine it is doing this because of the thermal shutdown that is sometimes on driver circuits. I coated the module in thermal grease before pressing it into a finned aluminum heatsink, but that didn't seem to help. Reading older threads gave me the idea that it could also be a poor connection. Any ideas on how to solve this problem?

 

[DTR]

Is it a fast strobe or a slow blink?

If it is a slow blink it is most likely the driver going into thermal shutdown but from what I have seen it should be at least 60-90 seconds @ 700mA from a cold start before shutdown. 600mA and under will run continuously not that it is good for the diode to do so. After it goes into a shutdown if it is not fully cooled down it will overheat quicker and may be what you are seeing. With running these fragile 405 diodes like we do we probably tend to push the duty cycle longer than we should.

If you do have a weak contact point that is creating a bottleneck in the host or a battery that is near dead or sagging a lot it can also make the driver boost harder which will create more heat.

 

[Rifter]

are you soldering on the power connection or using clips?

 

[Kevin520]

Is it a fast strobe or a slow blink?

If it is a slow blink it is most likely the driver going into thermal shutdown but from what I have seen it should be at least 60-90 seconds @ 700mA from a cold start before shutdown. 600mA and under will run continuously not that it is good for the diode to do so. After it goes into a shutdown if it is not fully cooled down it will overheat quicker and may be what you are seeing. With running these fragile 405 diodes like we do we probably tend to push the duty cycle longer than we should.

If you do have a weak contact point that is creating a bottleneck in the host or a battery that is near dead or sagging a lot it can also make the driver boost harder which will create more heat.

It starts slow, but gets faster as it gets hotter. I put a processor cooling fan behind it and that gave me a longer duty cycle, but it still blinks after a while.

 

[Kevin520]

are you soldering on the power connection or using clips?

I'm using alligator clips

 

[Rifter]

I'm using alligator clips

That's what I thought, try soldering them and see if that helps. I have found in my brief time with lasers that they are VERY sensitive to having solid connections and current/voltage supplied to them.

 

[Eudaimonium]

I'm using alligator clips

Which connections are made using clips, exactly?

IMMEDIATELY disconnect this and solder some wires on. Having a non-solid connection is almost always fatal for diodes.

 

[Kevin520]

Which connections are made using clips, exactly?

I was connecting the power supply to the driver circuit using alligator clips.

 

[Eudaimonium]

Driver is soldered to the diode firmly?

In that case, you have a driver overheating issue.

 

[Kevin520]

Driver is soldered to the diode firmly?

It looks to be soldered on firmly. I soldered the wires connecting the power supply to the driver to give it a solid connection. If I were to attach a small heatsink to the driver in addition to the fan, would that at least increase the duty cycle?

 

[Eudaimonium]

It looks to be soldered on firmly. I soldered the wires connecting the power supply to the driver to give it a solid connection. If I were to attach a small heatsink to the driver in addition to the fan, would that at least increase the duty cycle?

Yes, but you need to know how to attack it. You don't wanna short out the driver's connections.

Basically every driver has that one chip that produces all the heat, heatsinking that is a good idea.

Which driver do you have, again?

 

[busman2]

Had a M140 445 that was doing this exact same thing, turned out was just bad power supply, 2 x 16340 cells so I switched to a better quality cell, problem solved!
So maybe you just need a better power supply. Amps?

 

[Kevin520]

Yes, but you need to know how to attack it. You don't wanna short out the driver's connections.

Basically every driver has that one chip that produces all the heat, heatsinking that is a good idea.

Which driver do you have, again?

I don't know. I bought it off of DTR's Laser Shop. I chose the diode and the current I wanted out and that's it.

That one chip producing the heat should just be the voltage regulator, right?

So if I stick a small heatsink on that, given that I don't short anything, It'll give me a longer duty cycle, correct?

 

[Kevin520]

Had a M140 445 that was doing this exact same thing, turned out was just bad power supply, 2 x 16340 cells so I switched to a better quality cell, problem solved!
So maybe you just need a better power supply. Amps?

It's connected to a variable power supply, and a pretty reliable one at that. I started by connecting to the 5 volt fixed outlet with a max current output of 3 Amps. I switched to the variable ports though so I could watch how the current fluctuates when it starts blinking.

 

[ChaosLord]

If you got it from DTR, it should be a micro boost drive. Try a different power supply first. Heatsinking these are difficult cause there so small.

 

[WizardG]

My 445 did the same thing when I first hooked it up. The driver was inside the axis-Z module so there wasn't much room for a heatsink. I `fixed' the issue by simply filling the rear part of the module with cheap white heat sink grease. I figure that when the day comes when I need to service the laser for some reason I can clean the driver off with blue shower.