Another project red?

**FourDee** · 02-24-2010, 03:08

Nice work!
How many drivers are you using to power the diodes?

**MisterWilling** · 02-24-2010, 03:23

Originally Posted by MechEng3

Well I have a crystal set ordered...diode has been here. Should be able to cobble up 650mw of 532nm to go with it. I was planning to put them both in a box......I was hoping to get hold of a couple of BDR-205 diodes sometime...stable at 500mw each....then RGV in a big way....may not happen though...cash is getting tight with hopefully the last of doctor visits over soon. I may BST the 3/4 watt laser...not sure yet...

I have a couple of those bdr-205 on the way, from what I have read around they are rated at 320mW so I'm shooting for around 400mW per diode for a decent life. Hopefully 800mW 405 compliments my 200mW 473 enough to make a decent white.
Keep these updates on these reds coming

, I abandoned my multi-diode setup for my first scanner but I will definentally need to build one after all the info from you guys for my second scanner

**p1t8ull** · 02-24-2010, 07:03

Originally Posted by FourDee

Nice work!
How many drivers are you using to power the diodes?

And which common cathode driver is it - if it's CC as it seems?

Nice build Mike, it's getting me all itchy watching this progress

**andy_con** · 02-24-2010, 07:28

nice build.

am i correct in saying that all the diodes a touching and your using one driver for each set? so all the diodes could blow at the same time?

**MisterWilling** · 02-24-2010, 09:03

If I were to build a similar rig but instead have the aluminum block black anodized(free at my shop) and wire the cathode to each diode independently; would that provide better protection against blowing all of the diodes at once?

**logsquared** · 02-24-2010, 11:07

Originally Posted by MisterWilling

If I were to build a similar rig but instead have the aluminum block black anodized(free at my shop) and wire the cathode to each diode independently; would that provide better protection against blowing all of the diodes at once?

Do you mean a separate driver for each diode? Or, wiring the diodes is series? Depending on the sealer used in the anodizing process the aluminum oxide layer will be electrically non-conductive. Care must be taken that no burs or sharp edges on the diode module will scratch the mounts oxide layer. This type of isolation is what i plan to use for my finished combiner. I like the idea of series wiring to lessen the current needs of the driver and eliminate waste heat from the resistors needed in parallel wiring.

In my prototype I wired the diodes is parallel. All of the diodes that have failed on me in the past have still pulled current after they died. Even if one diode went open the total increase in current to the others would not be huge. I guess if the diodes were run at near maximum it could be a problem.

If wired in series or parallel a major driver failure could wipe out all the diodes. That would suck!

**buffo** · 02-24-2010, 13:15

I don't know what his plan is for this rig, but on a previous unit he wired the diodes in parallel with a small (1 ohm) current-balancing resistor in series with each diode. Also, on that laser each diode had a lasorb attached. I imagine the final product here will be similar.

And really, if you blow a diode or two while testing, it's not that big of a deal. They're less than $12 each, delivered.

Adam

**andy_con** · 02-24-2010, 13:42

but cost makes no odds really isnt it all down to reliability?

i would much rather a reliable unit where the diodes dont blow.

i think the best way is insulating each diode and using as many drivers as you can afford and lasorbs if you can afford it

**logsquared** · 02-24-2010, 15:57

If reliability is the biggest concern i would personally use two drivers. Series or parallel really doesn't matter then. If you lose one diode in series then you only lose half power. If in parallel then all the diodes are at risk of overpower depending on how many are paralleled and what the drive level is. Anymore than two-three drivers is overkill in my opinion.

When you glue the modules in to your mounts how do you assure the polarization is correct? Also, have you figured out what the thermal resistance is with that thickness of epoxy? I have used thermal epoxy for other tasks and it seems to work really well if its a very thin layer. I have thought about epoxying the diode module in a aluminum tube to allow for rotation in the mount. Never actually did yet.

**andy_con** · 02-24-2010, 16:01

Originally Posted by logsquared

If reliability is the biggest concern i would personally use two drivers. Series or parallel really doesn't matter then. If you lose one diode in series then you only lose half power. If in parallel then all the diodes are at risk of overpower depending on how many are paralleled and what the drive level is. Anymore than two-three drivers is overkill in my opinion.

When you glue the modules in to your mounts how do you assure the polarization is correct? Also, have you figured out what the thermal resistance is with that thickness of epoxy? I have used thermal epoxy for other tasks and it seems to work really well if its a very thin layer. I have thought about epoxying the diode module in a aluminum tube to allow for rotation in the mount. Never actually did yet.

indeed on my project im using two diodes per driver.

its not glue its thermal heat sink compound, the aixiz diode holders can be removed and spinned. the hole is 14mm and the aixiz diode housing is 12mm so its only a very thin layer

**logsquared** · 02-24-2010, 16:18

Originally Posted by andy_con

its not glue its thermal heat sink compound, the aixiz diode holders can be removed and spinned. the hole is 14mm and the aixiz diode housing is 12mm so its only a very thin layer

OH! That's really cool. How do you keep the diode centered? If you don't mind me asking.

It's really cool to see different approaches to solving problems. Engineering, experimenting and building laser stuff has to be equally as fun as the end effect.

By chance have you measured the temp. differential from the diode mount to the base? I am curious to know what the thermal conductivity of the compound is at 1mm thick.

**andy_con** · 02-24-2010, 16:30

Originally Posted by logsquared

OH! That's really cool. How do you keep the diode centered? If you don't mind me asking.

It's really cool to see different approaches to solving problems. Engineering, experimenting and building laser stuff has to be equally as fun as the end effect.

By chance have you measured the temp. differential from the diode mount to the base? I am curious to know what the thermal conductivity of the compound is at 1mm thick.

ive got some special clamps made to seal the aixiz housing to stop the compound going everywhere and to centre the diode housing.

ive not done any temp testing as the open can reds dont seemt to get hot. i had a dual setup running all day long at250mw at the last uk meet and at the end of the day they were hardly warm.

**daedal** · 02-24-2010, 16:41

Originally Posted by andy_con

i think the best way is insulating each diode and using as many drivers as you can afford

I agree... And here's what I'll be using...

http://www.daedallasers.com/laser-el...de-driver.html

--DDL

**FourDee** · 02-25-2010, 04:45

If I had the time, I would get to work on the multi-diode driver I've been thinking about for a while now.

It's expandable to suit any amount of diode, and it's a high side current sensing driver, so insulating of the seperate diodes is not necessary.

Unfortunately, I'm working on J1939 CAN-devices for my thesis and that's using up all my time.

I agree with andy that it is rediculous to power 4 or even 2 diodes from a single driver, especially in parallel.

**mccarrot** · 02-25-2010, 05:12

If needed I can supply you a HIGH QUALITY driver with 2, 4, 6 or 8 positive drive channels (modular), including tec control with cool and heat to keep everything between 19 and 21 degrees.

PM me if intrested

**andy_con** · 02-25-2010, 05:18

iinteresting can you post some details??

**hobbybob** · 02-25-2010, 05:22

Originally Posted by andy_con

iinteresting can you post some details??

Indeed, i just PM'ed McCarrot and now i see this post. I agree... very interesting....

**mccarrot** · 02-25-2010, 06:24

Demitry, I hope you dont mind I have taken your picture to point out the driver.
Bu the funny thing is you allready have this driver in your projector powering the KVANT.

The price is approx 250 euro for the 4ch version, this sounds allot of money, but if you take a quality positive drive driver(No offence but i not talking about Flexdrive or Die4drive as these drivers have little to No protection and are negitve drive) like Marcos this driver costs 50 euro each x 4 = 200 euro, then you need a die4chill a 50 euro = 250 euro, but then you have 5 seperate PCB's in you case.

**MechEng3** · 02-25-2010, 06:35

That certainly looks like a very nice driver to have. But one of the goals was to be able to make this laser without spending as much as buying a new unit. Mine is almost finished ,with exception of aligning, and have yet to burst the $250 mark. This was in the original post. This was intended to help others to be able to create a good laser at a very attractive price- given they can do a little machining and cobble a few parts. Just trying to get others involved building things.

**andy_con** · 02-25-2010, 07:01

that is a nice driver, but i would rather insulate each diode and use lasorbs due to cost

**buffo** · 02-25-2010, 08:13

Originally Posted by andy_con

really isnt it all down to reliability?

Reliability? That's what the lasorbs are there for. Having extra drivers doesn't buy you anything in terms of reliability. If anything, they add more components that could fail. (Though I agree that I've never seen a driver fail, so it's not a likely occurrence in any event.)

The only way you're going to blow a diode on this thing is during construction. Once it's assembled, aligned, and tested, you don't touch the internals again. So how is a diode supposed to fail, especially once you have the lasorbs installed?

Ok, maybe if you're greedy and you push each diode to 350 mw you might have a problem. But that's just stupid, and having extra drivers won't save you if you do that.

Running each diode at a normal current with a common driver and a current-balancing resistor works extremely well. And the lasorbs give you protection from the stray static shock that might otherwise kill a diode.

Adding separate drivers might allow you to tweak the current up or down on the diodes a bit, but that doesn't do anything for reliability. More to the point, is it really worth the extra cost in drivers just to get a few 10's of mw extra out of some of the diodes?

Adam

**hobbybob** · 02-25-2010, 08:32

@McCarrot: Ofcourse i don't mind if someone uses my pictures, i post them out in the open, glad it's there, use it when you need it ! My HD is filled with pictures of people of here, containing pics of builts, 4 diode setups, ally blocks that people made etc. So no problem.

Agreed with the others, i also want to built a nice red but cost efficient. I know "quality-minded" people are always talking about flexmods and die4drives as less and stuff like that. I have had lots of fun with Robin's drivers and also have ordered 2 flexmods from dr lava (will have to try those).
If i blow i diode, heck, too bad and i'll replace it. At 5-10 dollars each, i can blow a lot until i reach 250 dollars.

If you are selling a setup to someone that isn't able to built it themselves as a shop, like you are then i can understand you want a nice driver with stability and stuff. I know you yourself blew some diodes too, so can understand the stability point you are making from that point of view.

But i like the idea and vision that Mecheng3 had with this thread: let's all built together and share ideas and keep costs down to a minimum. I like that a lot in fact. Andy has helped me with terrific holders i will use and with the info here i hope to throw something together that will work.

So i think there are 2 streams here clashing together: DIY at low cost and DIY but with options to sell it as (semi) professional gear and it is no problem if it's a little more, as long as it's cheaper than the big boys in the market (being Kvant, Laserwave etc...)

**dave** · 02-25-2010, 09:01

This thread will provide me a little inspiration to proto up a common cathode driver when I get a few other projects cleared off my plate.. Maybe in a month or so.

**andy_con** · 02-25-2010, 09:10

Originally Posted by buffo

Reliability? That's what the lasorbs are there for. Having extra drivers doesn't buy you anything in terms of reliability. If anything, they add more components that could fail. (Though I agree that I've never seen a driver fail, so it's not a likely occurrence in any event.)

The only way you're going to blow a diode on this thing is during construction. Once it's assembled, aligned, and tested, you don't touch the internals again. So how is a diode supposed to fail, especially once you have the lasorbs installed?

Ok, maybe if you're greedy and you push each diode to 350 mw you might have a problem. But that's just stupid, and having extra drivers won't save you if you do that.

Running each diode at a normal current with a common driver and a current-balancing resistor works extremely well. And the lasorbs give you protection from the stray static shock that might otherwise kill a diode.

Adding separate drivers might allow you to tweak the current up or down on the diodes a bit, but that doesn't do anything for reliability. More to the point, is it really worth the extra cost in drivers just to get a few 10's of mw extra out of some of the diodes?

Adam

the thinking behind my post was running lots of diodes from one driving means the driver will need to dish out a fair bit of power, i then suspect it will need cooling and there is a greater risk of it dying. (just assumtion)

this is why im using lots of drivers.

also lasorbs wont automatically make the diode last long and protect from everythng.

im no expert its just how im doing it.

**mccarrot** · 02-25-2010, 09:19

Originally Posted by buffo

Reliability? That's what the lasorbs are there for. Having extra drivers doesn't buy you anything in terms of reliability. If anything, they add more components that could fail. (Though I agree that I've never seen a driver fail, so it's not a likely occurrence in any event.)

The only way you're going to blow a diode on this thing is during construction. Once it's assembled, aligned, and tested, you don't touch the internals again. So how is a diode supposed to fail, especially once you have the lasorbs installed?

Ok, maybe if you're greedy and you push each diode to 350 mw you might have a problem. But that's just stupid, and having extra drivers won't save you if you do that.

Running each diode at a normal current with a common driver and a current-balancing resistor works extremely well. And the lasorbs give you protection from the stray static shock that might otherwise kill a diode.

Adding separate drivers might allow you to tweak the current up or down on the diodes a bit, but that doesn't do anything for reliability. More to the point, is it really worth the extra cost in drivers just to get a few 10's of mw extra out of some of the diodes?

Adam

I do not agree here,

I had several diodes die in the past due to the fact I switched off the 5V PSU and this PSU put out a higher voltage on the driver causing the diode to die (at least I think that was the reason because I didnt disconnected any ILDA cables). Since I had installed the interlock circuit cutting the 5V to the driver I did not had broken diode anymore.

If it was that simple to use a crappy (read driver with no protection) + lasorb to make a good quality driver why do company's including Pangolin do so much effort to build quality drivers.

Lasorb will protect against ESD, not agains crappy drivers, any overvoltage to a driver can still kill your diodes.

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