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Killed 3 diodes...Any tips?

R

rockz

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So I got my driver built and everything so I began extracting the LPC-815's I got in a group buy. The first one was dropped a few times, and I think some dust settled on the die. It LED'd on me immediately. The second one was taken care of, but yet again it had LED'd, but there was a small flash of bright red light before it went poof. The 3rd one worked fine for about 5 minutes, but I forgot to remember that the case pin was negative, and sat it on the grounded case of the powersupply, the powersupply cut off in protection. even the millesecond amount of time, 30A of current passed through it and literally melted the diode pin straight off:yabbem:.

Needless to say, open cans are a pain in the @ss, my first PHR went smooth with no problems. Does anyone have tips on how to extract/connect/anything to reduce the chance of killing the diode?

All answers appreciated.
 





Gryphon

Gryphon

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LOC can be tricky beasts, they are very fragile. Their die is a bit longer than most
diodes coupled with the fact its exposed to the elements makes it that much more
sensitive. I remember seeing macro photos of a LOC that had its die broken into three
seperate parts by hair line fractures put there simply from having the diodes pryed out
of its heatsink. Your second one may have died from excessive current given that, as
you said, it did live momentarily. Your third one was just an honest mistake, we all make
those. Being especially aware of your setup and surrounds can take care of that. I my
self accidentaly hooked up a 1W 808nm on my power supplies 12V rail, needless to say i
realised it only a couples seconds too late.
 
Toke

Toke

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I just got 5 of those sleds, and have opened one so far.
If you secure it in a small vice it is rather simple to cut it with a small hacksaw, then twist it open with pliers.

I soldered a red and black wire onto the pins, then checked my driver with a bunch of diodes. For safety reasons my driver is made with 2 1,2Ohm resistors in series with a 0-10 Ohm trimmer, that gives a range of 100-500mA.
I think safe range for this diode is 400-500mA, at least it has worked for me for several minutes. :D

34ilrlx.jpg

I am not sure what the English name for the screw connecting tinggie is, but it is an ok solution for a fast test of diodes.
 
Toke

Toke

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420mA. And that tends to give 300mW?

Nice to know. :)
 
Eudaimonium

Eudaimonium

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Toke said:
I am not sure what the English name for the screw connecting tinggie is, but it is an ok solution for a fast test of diodes.
Click to expand...
Screw coupler, I believe (could be wrong though).

Your IC seems to be overkillingly heatsinked :D

I never even use any potenciometers in my drivers, I simply used fixed resistance and problem solved! No trimming and messing around with driver settings.

Just solder the correct resistor, and your driver puts out exact current from the start.
 
Cheech

Cheech

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Terminal strip is what we call them in Florida.
The LPC's that I have extracted are a pain in my ass. The heatsinks are the most awkward rounded not soft sent from hell...
I murdalized a diode like you would not believe. I'm scared about the hacksaw idea because they are open cans. So I use pliers, diagonal cutters and vices.
 
Toke

Toke

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Just solder the correct resistor, and your driver puts out exact current from the start.
Click to expand...
Sure, but I happen to like looking at a 6" spot on the wall while turning the pot up and down from 100-500mA. :D

I don't get it Cheech?
I placed it in a vice, applied a hacksaw*, almost to the diode, then used two pliers on the rather brittle poured aluminium.
If you turn it slightly face down in the vice there is no risk of getting "sawdust" into the diode.

*Small one, top centre on my picture.

Your IC seems to be overkillingly heatsinked :D
Click to expand...
I do not see the problem. :D
 
Eudaimonium

Eudaimonium

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Toke said:
Sure, but I happen to like looking at a 6" spot on the wall while turning the pot up and down from 100-500mA. :D


I do not see the problem. :D
Click to expand...
Ehh not understanding why you like looking at the dot.

I would not see a problem is the heatsink is one fifth of it's current mass neither :D Lower mass of stuff, greater portability when needed. Don't bump the heatsink with your elbow or something, if it falls over the table it'll pull everything with it.


Current setting with fixed resistance is by far the most preffered method by me. Rules out so many complications and impracticalities.
 
Toke

Toke

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Eudaimonium said:
Ehh not understanding why you like looking at the dot.
Click to expand...
Because I have just harvested the diode and build the driver.:D

I would not see a problem is the heatsink is one fifth of it's current mass neither :D Lower mass of stuff, greater portability when needed. Don't bump the heatsink with your elbow or something, if it falls over the table it'll pull everything with it.
Click to expand...
I have just gotten home from my ship, I brought it with me from an broken UPS and see no need to cut it to size, it is for labby jury rigging only.

Current setting with fixed resistance is by far the most preferred method by me. Rules out so many complications and impracticalities.
Click to expand...
Yes, once I have a driver to put inside a host.
Currently my MOSFET refuse to corporate in a joule-thief.
 
Eudaimonium

Eudaimonium

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Toke said:
Because I have just harvested the diode and build the driver.:D


I have just gotten home from my ship, I brought it with me from an broken UPS and see no need to cut it to size, it is for labby jury rigging only.


Yes, once I have a driver to put inside a host.
Currently my MOSFET refuse to corporate in a joule-thief.
Click to expand...
No I mean ehh, just build 400mA driver and have fun burning stuff ! :D

Well , yeah, it was more of a joke than a complain on it, no need to defent your point. Everybody loves big beefy heatsink.

Boost driver hmm, I'd go with some ICs if I were you, like LM3410X I use, they can take a lot, it'll give you much more power and control of the driver.
 
Eudaimonium

Eudaimonium

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Toke said:
That datasheet looks great, any idea where I can find them?
Click to expand...
Yeah, you can order up to 10 free samples from National itself, or buy from national semi's distributors like Digikey.

I got some samples, made sure they work, after making sure of that I bought 10 pieces of them from Bill who was making an order from Digikey so we both saved on shipping .
 
Toke

Toke

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Supply voltage say 2,7V, that is not a AA or AAA alkaline.
It may also be the reason my MOSFET doesn't work for me.
 
Eudaimonium

Eudaimonium

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Toke said:
Supply voltage say 2,7V, that is not a AA or AAA alkaline.
It may also be the reason my MOSFET doesn't work for me.
Click to expand...
Low input drives that boost from 1.5 V to needed are quite uncommon I think.

I haven't done any research on those so I can't help you there I am afraid :(
 
Toke

Toke

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Well, I will go buy some transistors tomorrow and see what I can get to work.
 
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