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



3.5W NDB7A75 445nm Laser Diode

rhd

New member
Joined
Dec 7, 2010
Messages
8,492
Points
0
So realistically what's the lifespan of this diode running it off a 3.5A driver that's well heatsinked? how many hours of MTTF?
This is not an appropriate question, and you should be very cautious of anyone who pretends to have an answer for you.

You've asked this same question in other threads. The very appropriate response you've received elsewhere is that it's not possible to estimate the lifespan of diodes that are being run outside of spec.

So if you just want someone to guess, you can guess for yourself. Take the estimated lifespan of the diode at datasheet current, if you know it, and pick a random number that's less than that ;)
 



FutureOne

Active member
Joined
Nov 2, 2010
Messages
175
Points
28
This is not an appropriate question, and you should be very cautious of anyone who pretends to have an answer for you.

You've asked this same question in other threads. The very appropriate response you've received elsewhere is that it's not possible to estimate the lifespan of diodes that are being run outside of spec.

So if you just want someone to guess, you can guess for yourself. Take the estimated lifespan of the diode at datasheet current, if you know it, and pick a random number that's less than that ;)
I believe I asked in a For Sale thread about this same diode (which I decided to ask more formally in this thread which is relevant to that item), and in another thread about the 520nm diode.

So it's not like I keep asking constantly.

And I totally understand the inability to get a "theoretical estimate". However, it would be nice to know how much practical times you guys are getting out of these.

It wasn't a big deal when diodes were $40 a piece.

But spending over $400 is more of an investment, and I'd like to feel comfortable that these diodes aren't going to burn out after 2-3hr runtime.
 

Shakenawake

Well-known member
Joined
Mar 11, 2013
Messages
1,889
Points
83
I'd say 3.5A is a modest overdrive compared to what the average diode goes through around here. mine has been going strong for a while now. it's only 16% over the recommended, much lower than the percentage many diodes are overdriven by. some are pushing these to over 5W, but I'm very happy with 4.7W
 

CDBEAM777

Well-known member
Joined
Feb 25, 2010
Messages
1,557
Points
113
It really is difficult to even guess. Each LD is somewhat different. RHD is spot on....MTTF will be less than what is posted on the data sheet...and even that is a statistical average !!! My guess is 1/10 of the posted MTTF....could be 1/100th !!!...who knows !!! Good luck !!:wave::wave::wave:
 

Attachments

Last edited:

Down with Umbrella

Active member
Joined
Aug 16, 2013
Messages
979
Points
43
It wasn't a big deal when diodes were $40 a piece.

But spending over $400 is more of an investment, and I'd like to feel comfortable that these diodes aren't going to burn out after 2-3hr runtime.
If you are concerned about over driving the diode What about running the diode at spec? According to the sheet it's maximum forward current is 3.0A. Also I see from DTRs testing 3.0A yields a power output of 4.2W. While its fair to say not every diode will perform exactly the same that value is still pretty powerful.

I feel 3.5A is pretty safe depending on how the module is heat sinked.
Just my thoughts. I've pushed diodes and asked myself the same question but that's part of the fun :p
 

rhd

New member
Joined
Dec 7, 2010
Messages
8,492
Points
0
Anyone want to review a driver?

It's a 4.5A buck that is so efficient you can hand hold the driver, un-heatsinked, for 60 seconds, and it will stay locked within 2% of its target current while you do that.

When heatsinked, it's stable indefinitely. It has a nice copper surface for easy heatsinking.

It's not tiny like some of the other drivers I've made, and each one takes quite a bit of work to assembled, but it's a neat little driver, and I have an extra (this is different than the one in my sig, though based on similar platforms).

 

Attachments

Last edited:

barthchris

Active member
Joined
Jul 9, 2009
Messages
152
Points
28
Good diode! Ive been running it at 4A for a week or two with lots of relatively long duty cycles. 60-90 seconds. Rick Trent AL heatsink barely gets warm. I really need power meter so I have no idea what its output is. Using a two-element lens with a Sanwa beam expander. Can burn a birch tree from 30'.. Good tree for burning names lol! Burned my sons names with a nbd7875 5 yrs ago and its still there but bigger from tree growth. Fun stuff...
 

RedCowboy

Well-known member
Joined
Jul 10, 2015
Messages
8,866
Points
113
Good diode! Ive been running it at 4A for a week or two with lots of relatively long duty cycles. 60-90 seconds. Rick Trent AL heatsink barely gets warm. I really need power meter so I have no idea what its output is. Using a two-element lens with a Sanwa beam expander. Can burn a birch tree from 30'.. Good tree for burning names lol! Burned my sons names with a nbd7875 5 yrs ago and its still there but bigger from tree growth. Fun stuff...
Yes the 7A is a good diode ( I also drive @ 4a ) and the 3XBE lets it reach out, even better use a G2 and C-lens pair and add the 3XBE to that and now you're cooking with gas, however just the G2 and c-lens pair makes a nice beam that burns well without making any adjustments.......that's what a laser is supposed to be, turn it on and use it fixed beam strong.

I really want to knife edge several but I've been enthralled in another hobby, however here's one from a while back > https://laserpointerforums.com/threads/7a75-corrected-w-3xbe.104181/
 
Last edited:




Top