Driver for the new 505nm and 480nm diodes

[paul1598419]

Stray capacitance? It's difficult to say without trying a process of elimination. I'd just chalk it up to one of those things....unless it is really bothering you. Then you'll have to set it up again and try eliminating things until it disappears.

This is a driver you built, right? Or did you get it from somewhere?

 

[Atomicrox]

Could be stray capacitance indeed.
I built it, yes, and further testing would require unsoldering and ungluing the heatsink/diode assembly, which I'm not going to do unless it fails Used a lot of glue.

I might do further testing if it survives a few weeks and I build a second one for the 480nm diode.

 

[paul1598419]

What's the footprint size on the board? Just curious.

 

[Atomicrox]

No board, just point to point soldered stuff. Will try to take a picture tomorrow.

 

[Atomicrox]

Here it goes. Looks (slightly) better IRL

 

[paul1598419]

I started my design for a PWM for my RGB 300 mW laser I got for $46.00. I believe I have everything I need to make a three channel PWM, one for each color that can adjust each color from no output to a maximum output in very small increments. I have a modulation frequency of up to 30 KHz to work with. I was thinking 10 KHz would be adequate, but might push that closer to the limit. Maybe 20 KHz. I can run the whole thing off a single 9 volt alkaline battery. I'm planning on using three NE555 ICs. Will update when I get it bread boarded and working.

 

[Atomicrox]

Sounds good. Aren't 9V batts very low current?

 

[paul1598419]

Don't need a lot of current to drive TTL inputs. It should be more than enough.

 

[Albert1007xd]

Podo from Sanwulasers told me that they are working on a new driver for those case positive 505nm, and they will work for all series except maybe pocket for size reasons, so that means that they will power them up from a single li ion battery... maybe they can start selling them, for compact builds using a single cell.

 

[paul1598419]

I doubt that very much. It would be very complicated to build a boost driver with a common positive side, that is the main reason you've never seen one before. I'll believe it when I see it. I still think the Blitz Linear driver is going to be the only option for quite some time, even though with the size of the board and pot, it is difficult to work with.

 

[Atomicrox]

Update on the LT3083 driver: I've been stressing this laser more than I usually do and so far it's running well. Analog modulation works properly and it seems reasonably stable. Today I ran it at max for about 4min and it went from 103mW to 94 (505nm diode with 3 elements lens). This is probably due to the thermal coefficient of the sense resistor as it warms up.

The only thing that may be considered a problem is that it flickers while adjusting the pot close to threshold. It's very hard to pin it at, say, 5mW. Above 10mW it's a lot smoother. This is probably just how these diodes work close to threshold and not a problem with the driver.

I'll call the driver a success and build another one for the 480nm.

 

[paul1598419]

I'm glad you were successful with building this driver. Good luck on your "480nm" build. Be careful, though. Those are no longer as ubiquitous as the "505nm" diodes are.

 

[Atomicrox]

Thanks!
I'll set it a bit lower. Don't want to lose that one.

 

[paul1598419]

I have mine set at 275 mA with a nano driver in a 501B host. It has been working well for months now. Just be sure your heat sink is good and the driver doesn't cause any spikes or glitches that might cause the current to increase.