Heruursciences diode grab bag thread

[cappernicus]

As long as there's no IR filter, I think a digital camera should at least see some IR even at 1500nm, IMHO. I only got one diode that didn't show anything through my digital camera and it is certifiably dead. It does get warm, but there is no light and no power with a power meter.

 

[Morgan]

Okay, thanks guys. I think from that I can determine that the few that didn't shine but did warm up are kaput. However, until I can actually PROVE it I'll keep them to one side.

I have done the camera mod by removing the IR filter, (and, "Yes", you can see through some clothes with it!!!), and placing some IR transparent/Visible blocking film in there and it works great. Just needed to check the range. If 1500nm is still seen then I have a base-line.

I have to save for a bit to get an LPM.

Yes to the goggles question too. I have some certified 200-540nm, 800-1500nm, +4OD goggles from Skylaser. I will post some sobering photos of one pair with a nice hole in them in my, "Ex government research laser", post.

M

 

[MarioMaster]

I didn't get any diodes in my bag that were above 1 watt (9mm cans) but that doesn't mean you couldn't get say a 2W in yours

 

[icecruncher]

I recently received my 9mm Grab Bag and Surprise Box, (some have seen and helped fire up the lovely HeNe tube I got, so thanks for that...).

I got one of those collimators too, (see post 5 or so above), so would be keen to see more posts regarding use.

Most of the diodes seem to be IR, (one red). Bit hazy on figures as I'm getting used to interpretting my new bench power supply but some are still getting brighter well above 2A. Does this seem plausible? Also, whilst I wait for my IR detector card, I'm using a video cam to detect IR. This is a pretty reliable way to, "SEE", IR but does anyone know if the sensitivity reduces as the wavelength goes beyond 808nm? The reason I ask is that some of the diodes respond, (and heat up), as if lasing but no light can be seen. Are these the duds?

Thanks all.

M

How are you testing with the PS? circuitry or straight off the leads?

 

[cappernicus]

Nothing above 1 watt??

If I did my testing right, most of the ones I got had thresholds at 400mA, 500mA, or 600mA. According to your chart, that would be 2W, 3W, and 4W? Am I doing something wrong or am I just lucky?

 

[heruursciences]

Be careful, The 4W are going to be QCW, the 9mm case will not support CW powers much above 2W!

 

[cappernicus]

Duly noted. I just think it's interesting that most of mine seemed to be 2W or greater when Mariomaster didn't get any above 1W. That's why I was questioning my test results.

 

[Morgan]

How are you testing with the PS? circuitry or straight off the leads?

Icecruncher - I am testing straight from the leads. (If you have a look in my thread re: Ex governement, blah, blah, there is pic of the PSU. Same setup just running straight to the 9mm diodes.) I can't say this is good, "method", but I'm open to suggested improvements.

Might be a good thread title actually? "LDs - How do you test yours?"

M

 

[cappernicus]

Well, I've gotten three grab bags and haven't gotten a single red.:cryyy: I have gotten to where I can tell an 808 just by looking at it though...

 

[HIMNL9]

Just a question for Heruursciences.

Maybe it's a stupid question, but i had this doubt: usually, aren't IR with positive on case, and red ones with negative on case ? ..... then, how can you test them without risk to burn all the ones of one type ? ..... i suppose you know if you invert the polarity, you burn them, so, if they are not marked for recognize what is IR and what is red, how they can be safely checked ?

 

[.3lite]

I've never burnt any of my diodes just by inverting polarity, so don't worry.

 

[dar303]

Use the diode test function on your DMM to find the anode and cathode.

 

[HIMNL9]

I've never burnt any of my diodes just by inverting polarity, so don't worry.

You're lucky, then ..... i burned 3 old low power IR ones, with this mistake

 

[cappernicus]

Use the diode test function on your DMM to find the anode and cathode.

That's what I do. If you have the polarity inverted, it will say it is an open circuit. If you have the polarity correct, it will give you the voltage drop.

 

[Krutz]

indeed, they "burn out when reversed". BUT: as well, they have a damage-treshold when hooked up in reverse. its in the mA-range or several times the forward-voltage (correct if off!). so if you use your DMM, it uses much less than one mA. no LD or LED or any (regular) devbice should be damaged with such low current. but then, i dont think this current is enough to see IR diodes glim. and it doesnt work with 405nm diodes altogether.
better idea: build some constant-current-driver which is limited to 1mA at a reasonably high voltage, 5v perhaps. reversing any LD with such current should be safe. i am not 100% sure, though, check this before you do it!

on topic: all larger diodes, no matter what wavelength, are case-positive. all multimode and all 9mm can should be. i bet someone will find an example where its the other way, but for us with these 9mm bags, i think case-positive is safe.

one day (when i get me some bags?) i will come up with a safe method to test LDs.. perhaps with quick heatsinking (plug the diode directly in without tools) and a safe current and enough voltage for any forwardvoltage (IR, red, violet)..

manuel

 

[HIMNL9]

Uhm, then is better that i build some kind of driver specifically set for test them at low current ..... it's not really easy to make a regulator for 1mA, cause almost all the regulators have a minimum load current of 10mA ..... maybe with an lm1117, that seeing its datasheet can drop til 2mA minimum load current ..... so, maybe with two in serie, the first as voltage regulator, and the second as current regulator with a resistor of 600 ohm, it may work ..... and at this current, the diode in any case don't emit laser light, so is also safe to look directly it