Open Can Issues

I'm continuing this from my "optiarc - no can" thread.

I got the open can out of another drive, and am having some issues.
I built the CCS w/ lm317 (3x10ohm resistors/no pot). I'm using 4-aaa batteries. When I test the circuit w/ no load, I get about 370ma and 5v.

I test the circuit w/ the diode in place and I get 200ma and about 2.6 volts.
Are the batteries not strong enough? I tried giving it 9volts, but with teh same batteries. Six instead of 4 AAA's. It made absolutely no difference.

Thanks!

That is pretty weird... especially because the voltage is so low as well as the current. You said you are using AAA's right? Maybe try it with AA's and see if that solves your problem. Or even just a 9v for simplicity (just for testing's sake)

the 9v brought my current up to where it should be, and the voltage was about 3.2. The diode still wasn't bright, tho.

when they go out, can you see the damage, or is it a change in the dope on the emitter or something? I took the diode out and looked at it under a 100x inspection scope, and it looks fine. The die has one wire on the bottom going to the positive terminal, and another tiny wire towards the top which connects to the can.

wicked1 said:

the 9v brought my current up to where it should be, and the voltage was about 3.2.  The diode still wasn't bright, tho.

when they go out, can you see the damage, or is it a change in the dope on the emitter or something?  I took the diode out and looked at it under a 100x inspection scope, and it looks fine.  The die has one wire on the bottom going to the positive terminal, and another tiny wire towards the top which connects to the can.

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sorry to tell you that your LD is turn into a LED. :'(

How did you powered up the circuit? Did you powered up the driver through the positive of negative?

It is sad!

I believe I powered it up through the positive.. I don't know for sure, though, as I wasn't really thinking about it.
Which is correct?

I powered it on out the lens assembly and noticed it was red at the bottom of the emitter, and at the top, but the middle was dark. I looked closely again w/ my scope, and there is a little horizontal line that goes across the middle of the crystal (or whatever it is). I'm not sure if thats supposed to be there, but if that is fragile, I could definitely see it breaking the time the thing flew out of my hands when I was dremmeling the case off. It shot across the entire room and landed on a concrete floor.

I had killed a few open can diodes powered it up through negative using an alligator clip.

I now powered up the circuit through positive using a switch between positive lead, haven’t kill any so far.

It could be the alligator clip making too many on/off switching. :-/
LM317 is positive regulator, I would think powered up through positive is better.

Thanks! Cause, that's exactly how I was testing it.
Same w/ the blue I killed.
No, actually, the blue was definitely positive that I was using to clip and unclip. But, still. I think it had something to do w/ me making the connection w/ the alligator clips.

I think I'll order replacement dvd drives, and not touch them until I get my kryton barrel and lava drivers.

My first built, I killed 3 Diodes. The fourth Diode went straight in side the host before powered it up.

No Diodes have been killed once installed in the host.

Good Luck

Ugh yeah, the temptation to just try and rig it up in some axiz module and some wires hanging out connected to some regulator circuit has killed so many diodes. Wait until you have a permanent host.

one issue i noticed with open cans is the mechanical fragility of the leads. I think they are epoxy or plastic set in the case as it's very easy to accidentally push in, pull out, or rotate them breaking the lead bonds to the chip during the removal procedure. :-/

heruursciences said:

one issue i noticed with open cans is the mechanical fragility of the leads. I think they are epoxy or plastic set in the case as it's very easy to accidentally push in, pull out, or rotate them breaking the lead bonds to the chip during the removal procedure.  :-/

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I'll second this. I just did my first ever open-can harvest. I had been too busy playing with other lasers to try this one! So one night I decided I wanted 300mW of red and set off to do so. I got the diode out and powered on for the first time, at only 35mA. Well I was messing with some stuff on my driver and it just went out. Hmmm..... So I tinkered some more and it came back on. Whew. I started turning up the current and got to around 250mA and it turned off again. WTF? this time I couldn't get it to light again. I thought it was my driver but I soon realized that the anode pin had rotated and (presumably) pulled the tiny wire off the die. Fiddle sticks.

GooeyGus said:

I'll second this. I just did my first ever open-can harvest. I had been too busy playing with other lasers to try this one! So one night I decided I wanted 300mW of red and set off to do so. I got the diode out and powered on for the first time, at only 35mA. Well I was messing with some stuff on my driver and it just went out. Hmmm..... So I tinkered some more and it came back on. Whew. I started turning up the current and got to around 250mA and it turned off again. WTF? this time I couldn't get it to light again. I thought it was my driver but I soon realized that the anode pin had rotated and (presumably) pulled the tiny wire off the die. Fiddle sticks.

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well that stinks, I always try to make a habit of as soon as I have the diode removed I press it into a module, solder wires onto it, and then add hot glue around the base to hold the wires in place so it not only prevents the leads from rotating but from snapping off from metal fatigue

MarioMaster said:

[quote author=GooeyGus link=1211552393/0#10 date=1214127968]
I'll second this. I just did my first ever open-can harvest. I had been too busy playing with other lasers to try this one! So one night I decided I wanted 300mW of red and set off to do so. I got the diode out and powered on for the first time, at only 35mA. Well I was messing with some stuff on my driver and it just went out. Hmmm..... So I tinkered some more and it came back on. Whew. I started turning up the current and got to around 250mA and it turned off again. WTF? this time I couldn't get it to light again. I thought it was my driver but I soon realized that the anode pin had rotated and (presumably) pulled the tiny wire off the die. Fiddle sticks.

Click to expand...

well that stinks, I always try to make a habit of as soon as I have the diode removed I press it into a module, solder wires onto it, and then add hot glue around the base to hold the wires in place so it not only prevents the leads from rotating but from snapping off from metal fatigue[/quote]

Just a note from your friendly neighborhood materials scientist:

You're typically not breaking these due to fatigue, but actually due to work hardening and the corresponding increase in brittleness.  Fatigue is only when you are elastically and not plastically deforming: if you bend it and it stays bent, you plastically deformed it.  If you bend it only slightly and it comes back to and stays in its original position, it's only elastic deformation.  Fatigue is due to repetition of elastic deformation only, when there is no plastic deformation.  When you bend these metals enough to plastically deform them, you are work hardening them.  Every time you plastically deform a metal (ie bend it and it stays bent), it gets harder, but also gets more brittle.  Do it enough times, and it becomes so brittle that it can no longer plastically deform and it simply breaks.

Fatigue also takes many more repitions than does fracture due to work hardening, like thousands.  So unless you are poking the pin a few thousand times hard enough to slightly jar it but not hard enough to permanently deform it, you are not fatiguing it.