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Venting

awlego

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Hey LPF... I need to vent after killing a few more lasers.

So I'm building a sweet RGB array with custom everything - drivers (FML style with effects and everything), heat sinks, fans, variable power for all the colors with the 445 pushing 1.5W.

I am on a time crunch trying to get it done for a laser show tomorrow and I lost all my red lasers. I killed one with a rough extraction, and the other two died somehow in my circuit. The circuit worked PERFECTLY for 2 days while I was machining my heat sinks and adjustable mounts, then when I tried to mount everything, it stopped working... and killed my lasers. My green/445 may have survived, but at least the red died. So I proceded to remove a red module from a pocket RGV that I had built earlier and stripped my driver down to the basic Lm317 base. I short the remove power, short caps, and plug it in... and it kills it! No changes from my original working circuit and what do I get, 3 dead diodes!!! ARGGGG.

I guess something must have changed in my circuit, because lasers don't usually spontaneously die like that, but it's still frustrating and I needed to vent.

So over my year or so building lasers, I think I have killed 6 LPC diodes... and me see... only 1 non-red diode. Granted a few of the reds' deaths were due to really stupid mistakes that I learned from (shorting caps, removing batteries, etc). But still.... Are these diodes unusually fragile? I have several green modules, a 445, and several blu-ray lasers and all have held up marvelously.

Ahhhh it's just so disappointing to lose a needed part the night before I want to test my new laser show set up.

Thanks for listening. I just needed to vent.
-Awlego
 

ped

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Vent recieved!

Your better speaking to andy_con or ElectroFreak , thier veritable experts in this field.
 

HIMNL9

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Basical question, but it come in mind speaking about RGB assemblies ..... are the bodies and heatsinks all insulated one from the other, or electrically connected together ? (red = case positive and green = case negative .....)
 

awlego

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At one point they were not insulated... which may have killed the diodes. I did some more testing and I did indeed kill all 3 of my diodes. $150 down the drain :'(

But while I was doing the testing I found that even when I had the heat sinks separated physically (not touching at all), there was still some way that they where not electrically isolated. At this point, I was testing 1 diode at a time, and so the only possible way that they could be connected that I can conceive of is through the 3 lm317s. I attached each of the lm317 chips to their respective laser heat sink since at 1.5amps and at .8amps the blue and green lm317's definitely need heat sinking. Especially kicking down from 12V.

Anyone have advice for electrically isolating these RGB setups?
 

HIMNL9

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If the 3 LM317 are in the same circuit, sharing the same GND connection, then they are not insulated ..... it must not cause problems, if the diodes bodies are not connected together, anyway (from heatsinks, or from a metal table, or from anything other)

About insulating heatsinks, i use Kapton tape ..... it's thin and resistent to heat, it left heat go from the modules to heatsinks, and if you take care to not "punch" it with set screws, it work very good ..... another solution can be using the Kapton tape between the heatsinks and the common base (this require plastic screws, anyway) .....
 

HIMNL9

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Just solder an 1Kohm resistor, also SMD, in parallel to the LD, and you're protected ..... add a 100nf capacitor and an 1N5408 diode (in antiparallel), and you're more protected than with any lasorb. (but don't use the 100nF capacitor if you need quick modulation)

;) :D
 

awlego

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When I finally attach them to the base I will be using nylon screws and washers which should isolate them. I still have to figure out how to isolate them with the lm317's attached, because they definitely need to be heat sinked.
 

qumefox

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I did some more testing and I did indeed kill all 3 of my diodes. $150 down the drain :'(
Um. Were these prebuilt modules modules or something? Last time I checked, LPC-815 sleds weren't anywhere near $50 each. Seems like I got a handful from somebody's GB not long ago that were $5 each or so. Personally, i'd be happy that the reds that died. I'd feel much worse if it was the 445.. or worse yet if it was a high power green.
 

HIMNL9

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When I finally attach them to the base I will be using nylon screws and washers which should isolate them. I still have to figure out how to isolate them with the lm317's attached, because they definitely need to be heat sinked.
Use pads and plastic washers also for the LM317.

If your store don't have them, ask for a broken PC PSU on any PC store, there's usually 3 or 4 sets for each PSU inside .....
 

awlego

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Um. Were these prebuilt modules modules or something? Last time I checked, LPC-815 sleds weren't anywhere near $50 each. Seems like I got a handful from somebody's GB not long ago that were $5 each or so. Personally, i'd be happy that the reds that died. I'd feel much worse if it was the 445.. or worse yet if it was a high power green.
I killed 2 reds, a 445, and a 100mW green all in one blow.

At first I thought it was only the red... but it was all of them.
 

AUTO XX

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Damn, sorry for your bad luck bro. I have killed 2 445s so far so I feel your pain.
On the upside, your build sounds awesome. Looking forward to pics/vid! :gj:
 

qumefox

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I killed 2 reds, a 445, and a 100mW green all in one blow.

At first I thought it was only the red... but it was all of them.
Ouch.. ok I can see that then. From your OP I thought it was just the reds.
 

Rafa

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Use Mica sheets and plastic washers for the LM's. You can get all of that from a computer PSU. All that I have opened had them inside.
 




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