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CLOSED: 4.5W 638nm Laser Diode

Jstr

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Re: OPEN: 4.5W 638nm C-mount Diode Group Buy

Okay, that's perfectly understandable, rhd. Thanks for offering the modules!

But what would be a good way to drive it in a handheld? a parallel setup maybe?

Also, i hope you dont mind my asking, but what exactly do you mean by the diodes are sensitive?

Thanks!
 



The Lightning Stalker

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Re: OPEN: 4.5W 638nm C-mount Diode Group Buy

But what would be a good way to drive it in a handheld? a parallel setup maybe?

Yes, that is how it has been done in the past. There was a build that used a stack of
AMC7135 boards to get higher current. I think some of the buck drivers may also be
paralleled, such as the X-Drives.

Also, i hope you dont mind my asking, but what exactly do you mean by the diodes are sensitive?

He was referring to a diode DTR used to sell. The older diodes are known to fail suddenly and
irrecoverably, unlike the more recent ones. We will get a better idea of what this one can do
once we have some to test.
 

rhd

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Re: OPEN: 4.5W 638nm C-mount Diode Group Buy

I think I would suggest the AMC route actually - or something linear. I wouldn't mind providing AMC drivers for the GB. We could even put some thought into getting their shape exactly the way we want them.
 

will manners

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Re: OPEN: 4.5W 638nm C-mount Diode Group Buy

Rhd means that they are very sensitive to current surges. Eg, if you want to power this diode at 5A than you will need a driver that slowly ramps up the current rather than giving it to it all at once. Other factors also come into it, such as how smooth is the output current after startup, is there any ripple in the output etc. EDIT: The AMC route sounds like a good idea. The driver that Lazeerer was working on for the c-mount 660nm diodes was supposedly AMC based as well.

As for driver setup there are not many (if any) choices at the moment for a handheld form-factor that will drive this diode at more than 3 amps. As for rhd's driver I think people should be able to purchase them (or make them) whilst knowing the inherit (seemingly non-existent) risks with using a driver that is relatively new and in only a beta stage. But ultimately (and obviously) that decision is up to rhd :)
 
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rhd

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Re: OPEN: 4.5W 638nm C-mount Diode Group Buy

I've missed much of the testing that went on with the other c-mounts, but is there any reason an AMC driver with a huge output cap wouldn't provide basically a soft start like feature that would be sufficient for these diodes?

A single 100 uF (EDIT: 220 uF) ceramic cap on the output?

EDIT: Digikey has a nice 1210 form factor 220uF ceramic. Something simple like this?

attachment.php
 

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The Lightning Stalker

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Re: OPEN: 4.5W 638nm C-mount Diode Group Buy

A single 100 uF (EDIT: 220 uF) ceramic cap on the output?

That is how the "soft start" in the DDL driver works. At 5A, 220µF would provide a 220µ *
2.5V / 5A = 110µs soft start.
 

rhd

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Re: OPEN: 4.5W 638nm C-mount Diode Group Buy

That is how the "soft start" in the DDL driver works. At 5A, 220µF would provide a 220µ *
2.5V / 5A = 110µs soft start.

Is that enough?

Here's a version with 2x 220 uF caps:

attachment.php
 

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The Lightning Stalker

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Re: OPEN: 4.5W 638nm C-mount Diode Group Buy

Good question. It's an eternity to a sled diode, but far shorter than the soft start of an X-Drive.
 

The Lightning Stalker

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Re: OPEN: 4.5W 638nm C-mount Diode Group Buy

:bumpit:

I have a new quote from the supplier. The OP has been updated to reflect this. If we can get to 20, that
will make it a full tray and the price will go down by at least another $20.

That driver board is looking really cool, RHD! Shouldn't the large caps be on the output side, though?
Thanks for your help to get this GB rolling!
:D
 
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rhd

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Re: OPEN: 4.5W 638nm C-mount Diode Group Buy

:bumpit:

I have a new quote from the supplier. The OP has been updated to reflect this. If we can get to 20, that
will make it a full tray and the price will go down by at least another $20.

That driver board is looking really cool, RHD! Shouldn't the large caps be on the output side, though?
Thanks for your help to get this GB rolling!
:D

Not a huge discount for 10x QTY, but better than nothing!

Caps are on the output side, yep. Between L+ and gnd.

If we're talking linear AMC 7135 boards, I'll supply one of those for each participant. I'm comfortable with that.
 

crazyspaz

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Re: OPEN: 4.5W 638nm C-mount Diode Group Buy

I wont be participating then, sorry- was hoping for a more substantial price difference.
 

Atomicrox

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Re: OPEN: 4.5W 638nm C-mount Diode Group Buy

At this price I think we should do the murder fund before the GB. I'd contribute but only if it's to the death.

We need to know if the divergence is reasonable and if it won't be as fragile as that other high power c-mount.... if it's that fragile it's probably not worth the trouble.
 

rhd

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Re: OPEN: 4.5W 638nm C-mount Diode Group Buy

I wont be participating then, sorry- was hoping for a more substantial price difference.

At this price I think we should do the murder fund before the GB. I'd contribute but only if it's to the death.

We need to know if the divergence is reasonable and if it won't be as fragile as that other high power c-mount.... if it's that fragile it's probably not worth the trouble.

It might be worth pushing back a bit.

Tell them "sorry, we were expecting more of a price benefit for increasing the QTY to 10x".

See what they say.
 

IsaacT

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Re: OPEN: 4.5W 638nm C-mount Diode Group Buy

What rhd said for sure. People want to make money. These things probably don't fly off the shelves of their own accord. If they see the sale walking they may change their tune. Then again maybe not. But the worst they can say is "Mk, see ya."
 

The Lightning Stalker

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Re: OPEN: 4.5W 638nm C-mount Diode Group Buy

It might be worth pushing back a bit.

Tell them "sorry, we were expecting more of a price benefit for increasing the QTY to 10x".

See what they say.

What rhd said for sure. People want to make money. These things probably don't fly off the shelves of their own accord. If they see the sale walking they may change their tune. Then again maybe not. But the worst they can say is "Mk, see ya."

That sounds like a good plan. I'm going to try and take a rest. I've been sleeping all day and
awake all night for the past few days.
:tired:
 

planters

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Re: OPEN: 4.5W 638nm C-mount Diode Group Buy

Lightning,
I'm one of those "projector" people. I was asked a few months ago to test the 5W C-mount that DTR was selling in a similar price range and which also came with a warning that the current had to be ramped up slowly. That diode had a FAC lens installed as a stock component and produced a peak wavelength @ 650nm. Despite my efforts with various cylinders and prisms, the divergence in the "Y" remained poor although the divergence in the "X" was remarkably good. It would have made a good source for a line scan projector. I strongly suspect that that diode's power came from a series of parallel emitters mounted on the same copper base. I am suspicious of this one as well.

If your source is interested in selling these then convince him to send you one or two and test them. If they are really good you will get A LOT of interest. If not, that will save everyone some wasted time. If they refuse, well...
 




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