SD 301 dimmed

[alessnilsen]

Thanks for the info, it's the lower one of the two shown above.

Then the plastic insulation is absolutely useless, as you can see, neither the "+" and the "-" of the LD touches the case, this says that the case is independent from the LD itself.

With a 2R2 load, current starts at 180mA and creeps up to 205mA where I stopped as a diode on the driver board was getting too hot to touch.

I tried the same with a 4R4 load and it started at 160mA and crept up to 190mA (again, hot diode).

I'm not sure the load is representative, if I remember rightly from my power supply design days having the output voltage of a boost circuit below the input voltage just ***** current through the flyback inductor and series diode which seems to be happening here. So I'll grab a few diodes and build something with a forward voltage closer to the actual load.

Yes, assemble a dummy load and post your results, boost drivers can't drop the tension correctly in order to keep the load constant.

 

[tttonyyy]

I've still not built the test load, but I did look at the other 301s and 303s I've got.

405nm 301 is insulated from the host, 303 heatsinked to host
532nm 301 and 303 are both heatsinked to host
630nm 301 and 303 are both insulated from the host

Whether this is true of all 301s and 303s for these wavelengths I don't know (anyone else got some they can take apart for a quick look?)

I dismantled the 630nm 303 and the diode had three pins in a straight line, two were driven -ve by the driver and one +ve shared with host +ve.

So I made up a copper shim to replace the plastic insulation.

The middle pin was connected to the diode case so I tried connecting that to +ve, but the diode didn't work when reassembled. Turns out the middle one is the pin that needs to be driven -ve for the diode to operate and is shared with the case. Can't do anything about that

For the 405nm 301 though I can use the copper shim in place of the plastic because the diode case truly does float. I'm not sure it's worth the effort replacing the toasted diode though for a crappy 301. Maybe if a bluray player comes my way I'll give it a go.

 

[alessnilsen]

I had a 405 303 that wasn't insulated from the host.

532nm (808nm pump LD) are case positive, 650 are case negative, usually, 405nm and 445nm LD's don't have anything connected to the case pin.

I dismantled the 630nm 303 and the diode had three pins in a straight line, two were driven -ve by the driver and one +ve shared with host +ve.

So I made up a copper shim to replace the plastic insulation.

The middle pin was connected to the diode case so I tried connecting that to +ve, but the diode didn't work when reassembled. Turns out the middle one is the pin that needs to be driven -ve for the diode to operate and is shared with the case. Can't do anything about that

Your result is correct, if the 303 was 650nm, then it MUST be insulated from the host, or else the driver will be short circuited, this explain why it doesn't worked.

For the 405nm 301 though I can use the copper shim in place of the plastic because the diode case truly does float. I'm not sure it's worth the effort replacing the toasted diode though for a crappy 301. Maybe if a bluray player comes my way I'll give it a go

You can buy it from China, here I found a 120mW 405 for U$9, I already bought from it and is reliable, but we must know the output current of the driver.

 

[tttonyyy]

532nm (808nm pump LD) are case positive, 650 are case negative, usually, 405nm and 445nm LD's don't have anything connected to the case pin.

Thanks, that's useful information

You can buy it from China, here I found a 120mW 405 for U$9, I already bought from it and is reliable, but we must know the output current of the driver.

The trouble is for $10.57 you can buy a whole 303 host and diode

50000mW Blue Violet Laser Pointer 303 405nm High Powered Focusable Burning Match Lazer Pen for Sale with Safe Key-in Laser Pointers from Office & School Supplies on Aliexpress.com | Alibaba Group (50000mW, lol)

...but I think I will save my money for now since I have two other working 405nms (I'm saving up for a nice big M140!)

 

[alessnilsen]

Thanks, that's useful information

I'm happy to help you! :yh:

The trouble is for $10.57 you can buy a whole 303 host and diode

You're correct! This is the way China works!

...but I think I will save my money for now since I have two other working 405nms (I'm saving up for a nice big M140!

Don't forget to keep your host/driver for future use, it can be very helpful!

:beer: