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ArcticMyst Security by Avery

Laser Loser & BR Blues

Joined
Jul 8, 2008
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An Xbox HD sled bearing an 803t arrived in my letterbox yesterday in the pm.  It was the last part I'd ordered to arrive, so, after the kids went to sleep I cranked on some 'Monster Magnet' and stuff like that and started work.

The BR came out of the sled and heatsink easily enough, and I managed to stuff it into the aixiz blank module.  This is where my troubles began.

I had crushed the PCB in my vicelike grip to such an extent that it came away in pieces when I got the soldering iron in amongst the pins.  It took me around 2 hours to get all the little threads of copper, resin, silicon and whatever else makes up crushed PCBs out of there.  It took so long, not entirely because of my frequent adjournments to refresh the old mug of Tequila and lemonade, but mainly because these tired old eyes can't see crap that small anymore  :eek:  Even with 3x magnifying reading glasses I struggled - well I could see the 3 little pins fine with the glasses on, but each time I looked away to pick up the soldering iron, pliers or scraping device, my eyes almost exploded from being unable to focus.  Returning the eyes to 3" from the LD was almost as painful.  So, I was sure that with all this heat I was pumping (although as intermittantly as my patience would allow) into the LD it was bound to be as fried as a fried thing's fried bits.  But I persisted...

Ultimately sucessful, my next step was jamming a (150ma max) adjustable Micro-Drive between it and a 9V battery.  Although I did also order a dummy load from Ryan (who was extremely helpful) I didn't use it because I didn't want to charge the cap with LD blowing potential and forget to short it out later.  That, and in my rather ham-fisted approach to this kind of stuff; knowing others have driven their BRs significantly higher than 150, I saw no marginal utility in starting off like a wimp.

Man, was I rapt when this thing lit up!  I stuck the mulit-meter in there and saw 141ma at VR min.  I screwed in the lens and had a hugely bright but disappointingly large image (>1")the far wall.  You know what a spiderweb looks like with dew or rain on it?  Just like this, only blindingly bright violet - anyway, that's a story for another thread.

I decided to solder in a switch so I wouldn't be twiddling wires together when I took it outside in the dark.  Did that and - - - dead!  Heart sank...

Turns out one of the joints from the driver to the LD was dry, because the beam came back on with some wiggling.  Yay!  Soldered it back up and it worked great.  A pale but visible beam in the post rainal slightly humid night aire.  Enjoyed painting violet spiderwebs over the neighbourhood for a while and then went in to do some work on my host (also another story).

So, tonight I'm working on the host again and decide to put some wires between the LD and driver and ditch the back cover of the module (rather than just leaving them hard-soldered together) as I wanted to be able to easily access the VR when I change one of the resitors to bring the driver up to about 200ma - I thought I should keep things at a sensible level (circa 190ma?) at least until I machine up a new heatsinkt.

But, before I could get the soldering iron close enough to inflict injury, the LR just stopped.  Just like that.  All by itself.  Ack!  So I wiggled the LD and got a flicker - the joint from it to the driver had cracked off again!  Soldered it back up.  Dead as a dodo  :'(  Unlike last night, the cap musta zapped.  Ack! to the irony...

Powered up again an hour or so later and got a flicker of light, but it certainly didn't lase.  Must have been its death rattle, because now it's not doing anything.

I'll have to order me up another sled, and gnaw my fingernails off for the 10 days or so until it gets here from the US of A.  Ack!  Better order a couple, given my propensity to screw things up...

At least I'll have plenty of time to finish knocking up (so to speak) my host.  1st hostal iteration will be plain vanalla; really just mockup.  But V2 will be a carbon fibre and machined aluminium 60s icon (but that, too, will be another story)  :-X

Regards
Richard
 





IgorT

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Yeah, well, like you said, it was the cap..

The connections between the driver and the diode should be permanent and perfect. You shouldn't even measure current there with the diode in place. If you're not sure, put a 1k resistor across the output. It will discharge the cap in a VERY short time, and not cost you a lot of current, only a few mA..

That's what i did, when i had to test 23 diodes in a very short time. If i did not put a 1k resistor on there, half my diodes would probably be dead, since i soldered to one, measured power, desoldered, and soldered to another.

After soldering, make sure the joints are perfect. If the wires go loose from wiggling, it's better this happens before the power is on...


Don't feel too bad tho. Killing diodes is a part of this hobby. The only 100% solution is to have a backup. ;)
 
Joined
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Thanks, IgorT.

Thanks also for the valuable information you've given me (unknowingly) as I've lurked, plotted and schemed. There's just so much to keep in mind when building that first laser, and mistakes to be made that hopefully won't be made again. I agree that making new mistakes is what this hobby is all about, but it's someone else's turn next time!

Thanks for the remider on the 1k resistor - that was one of the minor details that slipped out of my cognitive grasp on the day. I'll definitely be whacking one in next time.

Regards
Richard
 

Maven

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Jul 10, 2008
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maybe drinking and soldering isn't the safest thing to do ( for you diodes atleast)
 
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Good suggestion, Maven ;) It was more my impatience to get my first laser lit, and a lack of proper tools for the job. Without 3rd hands (or even locking pliers) I was trying to wrangle the components, solder and iron between 2 hands and a table. Not my best plan ever.

To add salt to the wound, I woke up this morning to see fog. Thick, white fog. The first (and probably the last) time this year. Don't get fog around these parts much anymore. Brilliant fluffy fog, and nothing but a flashlight to shine up it...
 

Maven

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... sounds horrible ... on most nights there is at least some fog where i am living right now, and on some nights the fog is so thick that you can't see more than 30 feet in front of the car...

hmm i usually do better just balancing stuff until it sits where i want it so i can solder it ... but then again i never much liked helping hands..
 
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Feb 11, 2008
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I solder the cap, snubber zener diode, and a ballast resistor directly to the diode pins dead bug style, then solder the works onto the + and - wires, glob it good with epoxy and masking tape and put the back of the module on. The laser module works directly off of 6V batteries or can be run off any available current or voltage regulator circuit that can supply an open voltage of 6V or more.

I usually use some medium strength double stick foam tape to hold the azix in place while soldering, the typical helping hands suck with things this small, but the lab type ones with the needle point grabbers work great!
 

Kenom

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I would be LOST without my helping hands. but I have helping hands that aren't your run o the mill hands.

DSC00288.jpg
 

daguin

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Kenom said:
I would be LOST without my helping hands. but I have helping hands that aren't your run o the mill hands.

It is ALIVE! [smiley=evil.gif]
 
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"Terminator 4 - The Beginning"  :)

I bought a cheap and nasty set of 3rd hands yesterday.  Work well.  Needed 'em to steady my hands after Maven cautioned me not to drink and solder  ;)

I've got more sleds and some 200ma drivers on the slow boat from China (well, the sleds anyway) so I'll have plenty of bits to play with soon.
 
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It's always sad when you realize your diode has had its last moments, never to lase again. :'(
 
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Jul 8, 2008
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Thanks, GG. As it was my first DIY laser it was especially hard to let go...

Can't wait for my ship(ment) to come in. With a few replacement parts on the bench I will be able to be recklessly free (err, to a certain extent anyways) :cool:
 




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