Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers

LPF Donation via Stripe | LPF Donation - Other Methods

Links below open in new window

ArcticMyst Security by Avery

Please help with my first build from scratch...

Joined
Aug 16, 2010
Messages
261
Points
18
This is my first build from scratch, harvesting the diode all the way up to soldering/setting the driver with a test load.

Its an LPC-815 diode, using a Flex driver set to 470ma (set using flaminpyro's test load on red) in Jayrob's stainless Aurora kit. Also using Jayrob's G1-650 lens.

The dot is super dim, barely as bright as my $2.99 ebay red, and its got some pretty knarly wings. No visable beam in pitch black. When I measure current at the tail cap I'm getting 182ma. The diode is getting warm, I can feel the heatsink heating up.

Where did I go wrong?
I want to get this figured out before attempting my next build I have sitting on the desk, its slightly more $$$ to ruin. (12x blu-ray)
 





rhd

0
Joined
Dec 7, 2010
Messages
8,475
Points
0
470mA may have been too much current for an LPC-815

Did you connect everything correctly?
 

anselm

0
Joined
Nov 22, 2010
Messages
2,448
Points
0
Reminds me of my experiment with a diode harvested from a DVD burner.
It was a long open can. Working fine at ~350ma, I wanted moar, gave
it ~420 and POOF.... is now dim just like you describe it, with the wings and all.
:whistle:
 
Joined
Aug 16, 2010
Messages
261
Points
18
Well I had read in the all diode thread that 500 was the max, and 420 was the norm, so I tried 470.

But why am I only getting 182 at the tailcap? I would hope its all connected correctly, everything came out just fine while on the test load.
 

rhd

0
Joined
Dec 7, 2010
Messages
8,475
Points
0
I think 380-420 would be considered the safe-ish range.

Someone may have been able to run their diode at 500mA (in fact I think someone recently ran theirs at 700mA+ with cooling) but that doesn't suggest that everything under 500 is safe.

I don't know enough about diode behaviour post-failure, but maybe once they're fried, they begin using significantly less current. Seems to make sense?
 
Joined
Oct 26, 2007
Messages
5,438
Points
83
First did you make sure you have the adequate voltage? The higher the current, the higher the voltage it uses. It's not a huge difference (e.g. 2.8V -> 3.3V), but if you've got tight margins with a linear regulator or something you may not have enough.

You get diminishing returns after 360mA, though it doesn't mean you won't get decent returns. That spot was chosen because it is right at the tail end before the mA/mW loses its linearity, i.e. the "hump". After the hump some other factors affect the efficiency of the diode, probably heat, so it'll probably shorten the lifespan of the diode to stray past that point. Still, given how little time people use these diodes in hosts and such, that loss of lifetime might be worth it for more power up front; plus those diodes are pretty cheap and easily replaced.
 
Joined
Aug 16, 2010
Messages
261
Points
18
My voltage at the battery I am using is 4.16v.

So what do you think? Can I turn the power down and try it again, or is the diode dead?
 
Joined
Jul 17, 2010
Messages
2,160
Points
0
If the Diode went LED it's done for! I lost an 815 on Sunday as I was fiddling with the focus I bump the current from 410ma to around 500ma that was all she wrote, and now I have a very nice red led to show for my efforts.
 

Tonga

0
Joined
Nov 21, 2010
Messages
537
Points
0
You guys have had some pretty freezing weather there, with those conditions comes propensity for static discharge. Could you have inadvertently zapped the diode?
 
Joined
Aug 16, 2010
Messages
261
Points
18
No I was pretty careful to be static free. I do alot of computer building/work so I'm always aware of static.

You know, one detail I forgot. Since this was my first laser I was kinda playing around with it. At different steps while setting the driver I would hook up the diode just to see it run. I'm pretty sure I hooked it up in the 80-90ma range and it had the wings and was super dim. It was in the heatsink, and I would only leave it on for a few seconds.
 




Top