Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers



3 in a row GONE!!

philguy

New member
Joined
Sep 16, 2007
Messages
415
Points
0
I don't know if thet helps, but one precautious step I did when harvesting from DVD drives is open the lid and fire the drive up to see whether red light is at all emitted. So if the diode won't work with the standard-circuit, not xyet being soldered on, it won't work outside, too.
 

Benm

Well-known member
Joined
Aug 16, 2007
Messages
8,115
Points
113
Might be a good idea to hook up your own driver circuit to the diode before removing it as well. That way, you can be sure that the problem is not damage in the removal process.

Also, if you solder the capactitor and diode (or resistor) across the diodes terminal at that point, you'll greatly reduce any risk of static discharge causing mayhem.
 

Kenom

Well-known member
Joined
May 4, 2007
Messages
5,629
Points
63
Ya cursed me Angel. I hooked it up to my dorcy and it gave a few seconds of really good power then instant led.
 

Gazoo

Active member
Joined
Jun 9, 2007
Messages
3,199
Points
38
I really wonder why this is happening. I have one I harvested over two months ago that is still as strong as the day I harvested it. On the other hand, I have one I was extremely careful harvesting and it won't even let me use it as an LED.
 

Kenom

Well-known member
Joined
May 4, 2007
Messages
5,629
Points
63
well, I've tested the circuit I was putting it into and It's putting out 380ma. I'm using the driver in the dorcy Jr. and it's supposed to put out 350ma. I've now toasted 4 diodes in this particular host and wasn't until I fried the IR from the same dvd burner that I started questioning why I'm burning these up. For an open can diode 380ma shouldn't be too much but apparently it is. I've not tested the voltage on the current under load yet. I'll do that next. but I'm obviously going to need to do some modifications to the circuit before i start putting new diodes in. I've tested another I just recently purchased and I've noticed two things now. . 1. the outside diameter of the head has changed. it is a fraction of an inch smaller and the driver circuit is putting out a bit more. (wouldn't be suprised if dorcy seeing thier famous flashlights being used as hosts for lasers is trying to prevent us from doing so. :) ) The other one I measured was a 390ma so it's defenitly a new circuit.
 

Kenom

Well-known member
Joined
May 4, 2007
Messages
5,629
Points
63
2.3v under load.  that is my new ir led. used to be a ld

so that's 2.3v at 380-390ma.
 

o_DEATH_ANG3L_o

New member
Joined
Sep 7, 2007
Messages
634
Points
0
LoL. Sorry Kenom. ;D. Hey at least you got to see your open can lase a little bit. Mine was already an LED before I hooked it up to power. :-[. Anyways if, and that is a HUGE if, I ever try an open can again, before even removing it from the drive, I am going to power it with daedal's circuit. That way I can be sure that my attempts before were failing due to the removal process and or soldering the leads on. I think I am gonna get some GB LDs off Greg.
 

Gazoo

Active member
Joined
Jun 9, 2007
Messages
3,199
Points
38
Hmmmm...I think there is something else going on with that circuit. I have run my diode as high as 500ma's (by accident) and have taken it through a few runs at 400ma's. Most of the time I run it at 300ma's. This is with a TEC and I am using Daedal's circuit, but it should easily be able to handle 400ma's without TEC. And I know you would be checking for heat. So I am certain there is something else in that circuit that is causing a problem.
 

Kenom

Well-known member
Joined
May 4, 2007
Messages
5,629
Points
63
well, I know with a plain ol multimeter I'm not going to be seeing any spikes. so I donno what to do. I'm going to be adding a capacitor onto the legs of my next diode and possibly a resistor or two ta boot. as recommended by senkat a 5ohm resistor.
 

Robk

New member
Joined
Apr 6, 2007
Messages
15
Points
0
Death Angel-
I didn't realize the power supply was fixed - no controls. I don't know your level of knowledge of electronics, and I certainly don't want to insult you in any way!
But, are you sure the LM317 circuit is wired correctly? How are you measuring the current to the diode? Ideally, you should place a .1 ohm / 1% resistor in series with the diode and measure the voltage across it (if you don't have one, I can send you one) - ohm's law dictates that the voltage in mV x 10 = mA current flow. Most digital multimeters are unreliable in current measurement except in the 10 or 20 amp mode where the shunt resistor is very low, but the accuracy is still questionable. I've burned up a few diodes, instantly, usually by shorting the power supply leads accidentally - when they "un-short", poof.
As someone mentioned before, you should place the cap (27 - 33uF) on the diode leads, also to be really safe put a 1N4001 across the diode in reverse. Sorry to hear about your 3 in a row - but there has to be a reason.
Rob
 

Gazoo

Active member
Joined
Jun 9, 2007
Messages
3,199
Points
38
I am using a 1 ohm 5% resistor, but it is still better than using the amp scale on a multimeter. Also that particular resistor does measure exactly 1 ohm.
 

o_DEATH_ANG3L_o

New member
Joined
Sep 7, 2007
Messages
634
Points
0
Thanks Rob. Yeah I am measuring the current on the 10A scale in series with the LD. I do understand it is more accurate to go the resistor route and measure voltage across it to get a better current reading. However I have done it both ways and on the 10 amp scale reading 0.20 would be 200 mA. All I really can conclude is that I ruined the diodes in the removal process. I checked and double checked my circuit. Everything is wired correctly. Oh well I guess I will not mess with open can diodes for a while.
 

Robk

New member
Joined
Apr 6, 2007
Messages
15
Points
0
A good source for .1 ohm precision resistors is a blown out Bass amp for a car. Usually they are used to balance 6 or 8 Mosfets in the output stage. I save old junk - it's amazing what you can pull from it!
Rob
 

Robk

New member
Joined
Apr 6, 2007
Messages
15
Points
0
Death Angel-
That would drive me nuts - I'd have to find out what happened! Good luck, again, I know how it feels to put all that time into digging out the diode and wind up with a dud. Keep at it - there has to be a logical reason.
Rob
 

yes8s

New member
Joined
Sep 22, 2007
Messages
73
Points
0
It's strange.

When someone figures it out.... let me know too.
 

o_DEATH_ANG3L_o

New member
Joined
Sep 7, 2007
Messages
634
Points
0
Well all I can say is good luck to those that do harvest open cans. They are very sensitive to everything, hence they are open. Well my only suggestion would be, to try and hook power to the LD while it is still in the drive to see if you can get it to lase. I am staying away from them for now though. Good luck everyone. ;)
 




Top