Laser Malfunction.

[Elyk456]

So I had finally finished my first build yesterday, a Phr set at 120mA, on a flexdrive...with a dorcy host. It was working great yesterday, very bright, and burned matches / popped balloons..but today I turned it on in the morning and it worked fine..then 2 hours later when I turned it on, it was working normal for about 10 seconds then it started shorting out a little bit, then it became pretty dim, and has stayed that way. It doesn't sting to touch and is pretty hard to see the beam. Now I only see 2 different problems here.

1. My battery is dead / dying. I think the battery might be dead because I used this dorcy LED a good amount before I assembled the laser.

2. The diode is a burn-out.


I really hope it is problem 1... :-/

 

[rog8811]

I hope you are right that it is battery related...But I killed 2 803T's@ 120ma...ever since I have used 110 ma as my max with no problems.

Regards rog8811

 

[Elyk456]

Well I mean this if my first build so I don't exactly know the symptons of a diode dieing  

Its in a darkhorse heatsink, and I barely used it...considering I built it yesterday. It only got warm about once, yesterday, and it worked fine after I let it cool down.

I hope it didn't die aready  



Can sloppy solder connections make it easier to burn out the diode? I might have heated the pins too long or something..I don't know at this point....its just alot less powerfull it was earlier. Maybe the "pot" is acting up, and it turned way low?



Oh, and if I do end up buying a new battery for the Dorcy, where would I get it, and is there any higher quality ones, or should I get the same one it came with: "Energizer Lithium Photo"



Edit: Yeah, after doing alot of reading, it seems when a diode dies, it does exactly what mine did. It shorts out, then is VERY dim. I just don't understand why it would die, I only used it for probably 10 minutes max of ON time, over the course of ....48 hours?

 

[ElektroFreak]

Well I mean this if my first build so I don't exactly know the symptons of a diode dieing  

Its in a darkhorse heatsink, and I barely used it...considering I built it yesterday. It only got warm about once, yesterday, and it worked fine after I let it cool down.

I hope it didn't die aready  



Can sloppy solder connections make it easier to burn out the diode? I might have heated the pins too long or something..I don't know at this point....its just alot less powerfull it was earlier. Maybe the "pot" is acting up, and it turned way low?



Oh, and if I do end up buying a new battery for the Dorcy, where would I get it, and is there any higher quality ones, or should I get the same one it came with: "Energizer Lithium Photo"



Edit: Yeah, after doing alot of reading, it seems when a diode dies, it does exactly what mine did. It shorts out, then is VERY dim.[highlight] I just don't understand why it would die[/highlight], I only used it for probably 10 minutes max of ON time, over the course of ....48 hours?

120mA is too much current for a PHR. That's why it died. Any time you overload any electronic component, you never know how long it will last. It could be less than 10 microseconds, or 10,000 hours, or anywhere in between.

 

[Th0ughts]

I thought that PHR's could be set to 100~140 mA with a good heatsink.

 

[ElektroFreak]

They can if you don't mind risking diode death. You can overload anything and it might work for awhile, but you just never know how long. As has been stated many times on this forum, PHRs are rated around 60mW output at best, NOT the 120-150mW many people claim. Running at any power above ~60mW is taking a gamble. Just because some people have a bit of luck at these powers does not mean everyone will... Laser diodes are not like computer CPUs. Extra heatsinking doesn't necessarily mean that you can overload it. All the heatsinking in the world won't save a diode if it is overloaded too much.

 

[Elyk456]

120mA is too much current for a PHR. That's why it died. Any time you overload any electronic component, you never know how long it will last. It could be less than 10 microseconds, or 10,000 hours, or anywhere in between.

Would 100mA be alot more reasonable? I know that all Phrs are different, but on average how much mW does 120mA and 100mA put out, and with 120 to 100mA, is there a big [highlight]visual[/highlight] difference?

 

[danq]

In my experience - which admittedly is not as much as others here - a current of 100mA is just about right for the average PHR.  Since the PHR's vary so much it's hard to say how much power you'll get out of it, but there's a graph around here somewhere that shows a current/power curve. If I can find it quickly I'll post a link to it... here it is, on this page:
 The XBOX 360 HD-DVD high power laser thread

DanQ

 

[Gloves]

hrm. so now that it's dead. Are you going to build another, bury that poor diode?

Thoughts, i'm with you on that one. A good heatsinc can solve many problems.

 

[danq]

Thoughts, i'm with you on that one.  A good heatsinc can solve many problems.

Unfortunately, this may not be among those.
Read Electrofreak's post.
Read through The XBOX 360 HD-DVD high power laser thread
...or just about anywhere that IgorT writes about 405nm diodes. Through many, many blu-ray diode tests he has found that there are factors that will kill the diode without it heating up. Heat may be a factor but decreasing heat will not necessarily save the LD. 120mA is pushing it, taking chances - many a PHR has died at 120mA without getting much more than lukewarm! 110mA may be ok; 100mA should be definitely ok. If you read enough of the posts here, that's what you'll find as the general consensus. but ymmv! good luck,

DanQ

 

[Blearyeyes]

Take it no one has managed to track down the spec sheet for the PHR diode yet. Seems like until somebody does, setting the current for them will be a hit or miss affair.

 

[danq]

Take it no one has managed to track down the spec sheet for the PHR diode yet. Seems like until somebody does, setting the current for them will be a hit or miss affair.  

<sigh> not at all - the diode has been fairly well-characterized, including the fact that they are somewhat variable. Some appropriate thread-reading would help your understanding of the subject...
;-)
DanQ

 

[ElektroFreak]

Take it no one has managed to track down the spec sheet for the PHR diode yet. Seems like until somebody does, setting the current for them will be a hit or miss affair.  

Quite true.. All these people who insist on believing that PHRs can reliably do 150mW out or handle 130-150 mA current are very much mistaken, and running them at these powers is a gamble at best. While we do not have datasheets for PHRs, the general consensus among the experts is that they are most likely rated at 60mW max output at around 90mA. While 150mW of 405nm light seems awesome from a diode for the price, a 60mW violet laser for ~15.00 is still an absolutely killer deal, plus you're likely to see a long lifetime at these powers. I have one that has been powered up for 3 months continuously at 80mA. That's roughly 2100 hours with no problems and no power loss. It still burns quite well when focused, even though it's putting out about 65mW average after optics.

 

[Joe]

I too built my first laser yesterday. It worked great for a bit, then while I was playing around with it I went to turn it on and...nothing. I had an LED.
I was using a PHR-803T, DarkHorse heat sink, and a Dr. Lava drive.
I ordered the Dr. Lava preset to 110ma.
I remade the laser this morning and it works. I am just afraid to play with it now.
I think a connection came loose last night causing the fail. Everything is solid now, but I am still scared. I hate that feeling you get when all of your hard work goes down the crapper. :'(

 

[Blearyeyes]

[quote author=Blearyeyes link=1231529255/0#10 date=1231867288]Take it no one has managed to track down the spec sheet for the PHR diode yet. Seems like until somebody does, setting the current for them will be a hit or miss affair.

<sigh> not at all - the diode has been fairly well-characterized, including the fact that they are somewhat variable. Some appropriate thread-reading would help your understanding of the subject...
;-)
DanQ[/quote]

I have and I stand by my original statement.

 

[ElektroFreak]

[quote author=Blearyeyes link=1231529255/0#10 date=1231867288]Take it no one has managed to track down the spec sheet for the PHR diode yet. Seems like until somebody does, setting the current for them will be a hit or miss affair.  

<sigh> [highlight]not at all - the diode has been fairly well-characterized, including the fact that they are somewhat variable. Some appropriate thread-reading would help your understanding of the subject...[/highlight]
;-)
DanQ[/quote]

Blearyeyes has the right idea..
All of the "experimentation" that has been done on these diodes is no substitute for a datasheet. You can experiment all day long, but you'll still never know exactly what the true specs are. If you're interested in maximizing lifetime (which I very much am), then you need to know the true specs. As I've said before, laser diodes are manufactured to last 10,000 hours or more, but this is only obtainable of you don't EVER overload the diode. Many people are of the opinion that PHRs are so cheap, why worry about it. you can just replace the dead ones. This is true, but from a pure electronics engineering standpoint this is a terrible way to go about building an electronic device. I'm a bit OCD about things like this myself, and I will not design a circuit that is weak and potentially unstable. This means running each end every component in the circuit slightly below rating to maximize reliability and lifetime (also called over-engineering). This is why I run all of my PHRs at 80mA. This means that I end up with a 405nm laser with the reliability, stability and lifetime of a MUCH, MUCH more expensive laser. All this is achieved by not being too greedy about how much output the diode gives. If you want a 150mW+ violet laser, then buy a higher powered diode like a 4X or 6X. They are designed to handle the extra current, but they are still without datasheets and a bit of a gamble themselves..