quad 445 build

[andy_con]

4 diodes

 

[Drew]

That's putting those flex mounts to good use! The last pic looks like the laser closest to the driver could use a little focusing?

 

[BennyF]

That looks awesome. have you had the chance to see the power output of it yet?

 

[anselm]

Great build, getting better every time!
Hmmm, parallel...
What happen's when one diode goes, do the others follow right after when they run at 133%?

 

[rhd]

Hmmm, parallel... What happen's when one diode goes, do the others follow right after when they run at 133%?

Exactly my first thought.

But then it occurred to me that the FlexMod is limited to 4A, so he's driving these (presumably) at 1A each.

If one dies and pushes its current to the other three, that's still a safe 1.33 A each - wouldn't kill them.

Plus, when diodes die, they don't usually stop taking current anyway.

 

[GBD]

So why not run them in series at a higher voltage (to compesate for the forward voltage of 4 diodes). This will keep the current the same, easier to drive and modulate (although I dont know if the flexmod can boost the voltage that high). That, and it is generally better then parraleling diodes off one source, each diode's Vfwd will differ a little bit and will cause others to run at different powers, or one diode will hog the power and overload itself.

(Ive had that happen in the case of LEDs and rectifier diodes, where the diode with the lowest forward voltage in a parralel bank drew most of the current, and promptly fried itself (raw diode array, no limiting of any kind aside from the power source).

Maybe I am missing something about this build, but generally running diodes (any diode) in parralel from the same source without any ballancing/individual limiting is a bad idea. A series bank eliminates most of these issues, as your bank behaves more or less like one diode with the combined Vfwd of all the diodes used.

EDIT : Bah, NVM, for some reason not all the pictures loaded for me and I see he is using some resistors there for each diode, this is okay too

 

[jayrob]

Wow man that's cool!

How about a little information on the build? I see resistors...

All 4 diodes running parallel correct? Current? Output power?

Nice build!

 

[jib77]

Great build, getting better every time!
Hmmm, parallel...
What happen's when one diode goes, do the others follow right after when they run at 133%?

Looks like each diode has its own current limiting resistor.

 

[vincenthooi]

this epic thread demands a power test and a burn demo

 

[Gryphon]

Now just stick it in the head of a maglite and your set

 

[Trevor]

Now just stick it in the head of a maglite and your set

Everytime someone says that, someone on PL dies a little inside.

-Trevor

 

[rhd]

Everytime someone says that, someone on PL dies a little inside.

-Trevor

And someone at CPF laughs

 

[Meatball]

Are there any secondary optics? Or does the entire beam expand into a giant horizontal line after some 10m?

 

[Kevlar]

I love seeing your multiple-diode builds Andy. Good stuff. :beer:

@Meatball, he is probably using similar optics that have been in his other multiple-diode builds.

You can see them here in 8 LOC build. http://laserpointerforums.com/f50/octuple-red-build-60584.html

 

[rhd]

Does anyone know where to source similar small square mounts cheaply? They don't have to be PL quality

 

[BShanahan14rulz]

Andy, I know lots of people ask you what knife-edging is. Well, I was wondering, what exactly is kn--- just kidding. Just wanted to comment that your last picture is probably the best pictorial representation of knife-edging.