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Who wants to take this project on; host for 15W IR C-Mount Diode

TheDukeAnumber1

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Thank you for sharing, do note though that you've already been asked not to double post. That's what the edit button is for.
 



Alaskan

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Edit: Anyone who wants to see that project, PM me for the password, I just locked it again: http://imageevent.com/qdf_files/technicalgoodies/experimentersfolder/irandlightwavecommunications/irledandlaserproject - I just ordered another bunch of diodes; twenty 445nm 2 W assemblies and will be adding more later.

Mr. Duke: I posted the wrong link, I should have just edited it instead of deleting and starting over. So many critical comments (not yours), I've never seen so many in any forum, is this normal here? This comment is probably just more bate for the wolves, but really. OK: Due to your request (again) from my not following others instructions or forum protocol... I deleted my double posts and edited them into one. I have a hard time following rules, please forgive me, this goes for my projects too, they tend to be a bit out of the normal envelope. Don't ask why, crazy people never need explain themselves, do they? Some of my stuff is related to work, others just for fun and you don't need a reason to have fun.
 
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rhd

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It's fine if you have a current-balancing resistor on each diode. 1-2 ohms is typical for high powers.
That's not the issue.

In constant current regulation, when diodes are paralleled, if 1 of 10 diodes die, the remaining 9 each get 10% more current, which can cause cascading failure.
 
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Cyparagon

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when diodes are paralleled, if 1 of 10 diodes die, the remaining 9 each get 10% more current
Only if the diode were to fail open. That pretty much never happens.

(edit: got it backwards)
 
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rhd

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Only if the diode were to fail short. That pretty much never happens.
Huh? If the diodes are in parallel, and the driver is set to output a constant current, failing open is the problem.

As the simplest illustration, imagine two paralleled 9mm diodes and a constant current driver outputting 4 A. When the diodes work, it's reasonable to assume both will get close to 2 A of current.

If one diode fails open, then the whole 4 A goes to the remaining diode.
 

TheDukeAnumber1

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I believe they can fail optically and still take current. The diodes I've popped in the past never failed open.
 
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Cyparagon

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Whoops, you are correct. I've edited my post above. They don't really fail open either. They just quit lasing. I've never had a laser diode fail either open or short. Maybe if a wire came loose, but that would be bad no matter how many diodes you were powering.
 
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The Lightning Stalker

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I have made heat sinks for c-mount diodes before, but I only have manual equipment and it takes time. A
heat sink is far from a host, but it's the minimum requirement to run a diode. Keep in mind there are no
off-the-shelf 16A capable driver boards currently available.
 

Alaskan

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My apologies for the misconception, I didn't mean I was feeding them power in parallel, each has their own current regulator. What I meant was all 16 output beams are in parallel or not combined together. However, I have some mirror knife edge combiners I just bought and am going to run eight M140 outputs together into one output stream just for the fun of it.

I can make a current regulator which will do 16 amps, I used to design my own circuit boards 30 years ago, etching them myself. I am familiar with various regulator designs, have used high power MOSFET's before for current regulation. Building a regulator isn't a challenge for me, learning about lasers themselves is new to me, only started with them about 2 years ago and don't spend most of my time dinking with them. Most of my professional background is in RF, that's where I design most of my stuff, the last project I did was a 6 KW output class AB2 linear power amplifier with 2 amp CCS 4 KV power supply.
 
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Quaxo76

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However, I have some mirror knife edge combiners I just bought and am going to run eight M140 outputs together into one output stream just for the fun of it.
Tired of popping balloons and trying to pop truck tires, are you? :p :)
 

rhd

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A linear regulator seems like a bad way to go when you have a ~2 V differential between battery voltage, and Vf, at 16 A. You'll burn 30 Watts as heat before you even factor in the laser diode.

If you're trying to make this portable, you need something more efficient than a MOSFET driver in my opinion. 30W is a about the same heat as 4x high powered 445s would create, and remember, that's just your driver.

Sent from my Nexus 5 using Tapatalk
 

Alaskan

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Thanks, I haven't really sat down and crunched the numbers yet, getting ready for a trip to Dubai this week. I imagine I won't tackle this for another six months or so but will be doing research in the mean time. Combining 445nm diodes is just for fun, I've never tried popping balloons yet, believe it or not, although I have burned through some card board, that's about it for destroying anything.

I have three of these 15W laser diodes now, I will probably mount them in their own C-Mounts, active cool them and then combine the outputs somehow. The input voltage will likely be in series through all three for somewhere close to 6 VDC and constant current, of course. I don't know if I will push them to the full 16 amps or not, maybe... Perhaps go for more and pulse them for higher output but I haven't researched that, it's all up on the air for me how this will be done or what I will end up doing. I usually brainstorm projects like this for weeks to months before I build something.
 
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The Lightning Stalker

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A buck driver is definitely the way to go here. The community is in need of a driver which can output more
than 3A.
 

rhd

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I have three of these 15W laser diodes now, I will probably mount them in their own C-Mounts, active cool them and then combine the outputs somehow.
So they're not already mounted on C-Mount packages?

If you're going to go to the trouble of trying to combine the three outputs, why not just get a 40W diode bar with a FAC ?

I don't have any experience to back this assertion, but I would bet that the output of a single FAC'd diode bar would still be better than the combined output of 3x 15W diodes.

How much does a 15W IR diode cost? 40W bars are not too pricey.

A buck driver is definitely the way to go here. The community is in need of a driver which can output more
than 3A.
I've got a prototype buck PCB en-route that will do 120 mA to 5A range, set via multi turn pot :)
 
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Wolfman29

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What size would people need for a high-power buck? I've a few designs that work, but I just never put them into production because they were too big for handhelds.
 




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