Is there anyway to do a quick 2-3 second test of a LD without driver?

[Jinx]

New Here, about to start building my first basic laser (not sure what its MW power will be it came out of a 16x cd writer).

I know i'm going to be told "Never run a laser without the driver" but is there a way i can use like maybe a single 1.2 volt battery and a couple resistors on a bread board to simply quickly test the laser diode to make sure it is the right one and working? (i took apart a 16x cd burner and there was 2 laser diodes in there so i'm not sure which one is the burner one) and I also want to make sure i haven't shocked it or ruined it before i start dropping money on 3.7 volt batteries, a charger, a driver .. that kind of thing..

Just looking for a possible simple way to use some stuff i already have (lots of resistors) to just simply quickly test the diode, it doesnt have to burn or anything like that, just want to see if it lights up is all..

thanks in advance!

 

[JLSE]

For a 16x red, you dont want to go much over 200mA, 250mA at most..
Any testing without a current regulated power source is risky, especially
on the lower power diodes.

Make yourself an LM317 driver, and keep it just for testing.. This is the safest
route. The circuit is simple to make and use.

:beer:

 

[Jinx]

But i'll need to get some of the 3.7v batteries for this right? cuz the lm317 requires 7.4 volts or close to work? Thats why i was hoping to be able to just test the diode before i spend all that money (gonna cost me at least 20-25 ish to get the parts and batteries and charger).

 

[JLSE]

If you have some computer parts, you can use the power supply from a PC. Hook into
the 11.85v rail, and the 317 will do the rest. You can also run it off of 4x AA 1.5v
batteries.. 6v should be enough for testing.. You may be able to use the 5V rail
as well, but I cant be for certain. Its been some time since I use a 317.

Keep in mind at near 12v, theres gonna be some heat to manage on the 317.
A small heatsink will suffice.

* Just remember to short the caps before hooking up your diode. A stored charge
can kill the LD.

 

[proud2deviate]

^ Agree.

You should be able to build a simple LM317 driver for less than $5. You can even omit the potentiometer for a fixed value resistor, and never have to worry about resetting it. If you need the schematic, just search Google Images for DDl Driver. It should be in the first few hits.

 

[sinner]

Always keep your step by step guide, as a noob i used to kill more diodes because i never actually followed any SOP's in handling laser diodes.

If the process/testing/experimenting require a particular standard of operation, you should learn it and follow it. There is no other way arround.
eg: LM317 needs 5.8V @250mA to keep in regulation, since this can be accomplished very easily by using a 4x 1.5V alkalines, but lithium are recommended.. Now WHY the hell everyone emphasizes on Lithiums is Because as soon as the Primary Alkalines drop to 1.44V the DDL will be out of regulation.. while there is still 90% of the battery still remaining.
Now on the other hand Lithium batteries will:
Supply enough voltage and current even when they are empty (3.7v)
Have a higher capacity that will last quite longer than alkalines
Rechargeable upto several hundred times.


So if the process needs the lithium ion batteries, You sure can use a 12V source but when it comes to batteries they are worth spending 20-25-ish!

 

[Jinx]

Thanks guys, It wasn't so much that i didnt want to spend the money on them, but if my diode is already toasted (no real reason to think it is but i like to be sure) Then i'd be out the diode and 25 bucks worth of parts that might not get used, AS this was kind of a first try experiment and looking off the some of the guides that made it seem like for 5 or 6 bucks you could build a balloon popping laser i'm now looking at it costing around 30 total and just hoping that everything works when i put it together..

As for a heatsink for the lm317 how would i attach? I have a heatsink from an old dell thats pretty large :

not sure how i'd use it..

 

[Just4FunReally]

Well, if you have a bench power supply, you can hook it up to that without a driver and then slowly raise the current to what has been suggested previously. I don't think it's likely that you do, but if so that's the best option. :beer:

 

[Jinx]

You're right i dont have that i'm thinking i might just hit the electronics store tomorrow and get the peices for the lm317 and see if there's any other way i can rig up some of my 1.2 rechargable AA's to be the powersource for a small test..

Btw anyone have a guess which one of these is the burner diode?

I thought it was a 16x CD burner but on second thought it might have been a 16x DVD burner..

 

[Just4FunReally]

The one with the three pins and the largest heat sink is usually the rule of thumb for the desired diode. It is certainly one of the two three pin ones. The 4 pin is the CD IR diode. If you want to run an LM-317 off of something a bit easier to get, 4 AA or AAA batteries in series will work. Just get something that holes 4 and wire that up, or two that hold two and wire them together in series. AA's and AAA's are pretty easy to acquire.

 

[JLSE]

Look at the reflection of the coating on the diode windows.. The darker bluish
is your red.. My guess is the one on the right, can only see the slight reflection
of the one on the left.

If it was a 16x DVD burner (most likely) the CD rate would be a 48X
or whatever that stagnant number has been at all these years :can:

 

[Jinx]

Ahh so does the dvd burner diode also burn the cd's? or does that mean the cd diode is a burner too and i could make 2 lasers? I only see the 2 diodes with 3 pins, where's the 4 pin one? not that i need the 4 pin though...

I cant tell that either is any darker, though looking inside the housing they were attached too one is a larger hole than the other? i tried to take some better angled pics..

Btw thank you guys for your help with this, i'm a newbie but this seems like a fun project! And i should be buying all the parts from the LM317 DDL circuit picture found HERE: Laser driver - It can be done right?

 

[JLSE]

Pic below should be your red.. The bottom pic in your post should be your 780nm NIR, remember you wont
see much light from this one, but its emitting infrared, be careful.

Also, if you dont know where this sled came from, it could also be a DVD/CD reader..
If thats the case, both will be 5mW or so.

 

[Jinx]

I actually took the whole drive apart, its DEFINATELy at 16x burner, just cant remember if it was CD or DVD but i think it was DVD burner.. I tossed out the extra parts, cuz I totally forgot i might need to reference the info.

So even tho in that picture of mine the middle one looks more blueish you're sure its this other one thats gonna be the burner diode?

 

[Jinx]

And at that, what would be a good guess for the specifics of powering the diode? 125ma?

 

[JLSE]

The pic I reposted is the more bluish coating, that is your red.. If the drive was a
rated 16x DVD burner, then you're good till 200mA or a tad more.

If you give the red 200mA and the diode blows, than it was a really low power red
and no big loss anyway..

I'd set your driver up, get it tested to the desired current and hook up your diode.
Go from there, if the red blows, just get another. Most high power reds can be had for less than 10$