FlexMod N2 Laser diode drivers have now arrived :)

'Good news everyone!' The FlexMod drivers have arrived and I will ship the outstanding orders shortly. Thank you everyone who had to wait. This is a high speed laser diode modulator capable of driving high and low current diodes for direct injection lasers and DPSS modules.

Specifications:

* Power input: 5-12VDC
* Analog Input: 0-12V max, usually you set to 5V full range
* TTL input: 0-5V Off-On
* Gain setting: 11 turn pot with 2 ranges 0-1A, 0-6A output.
* Bias setting: 11 turn pot range 0-2A output
* Dimensions: 31x21.5mm


http://hacylon.case.edu/laser/FlexModN2/modu.jpg

Available here

Cool! More current!

Oh cool, a newer model? It was worth the wait then.

nice same price?

and can you explain the differences?

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Originally Posted by thesk8nmidget

nice same price?

and can you explain the differences?

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Hi, yes same price, also if you have any unused V1 drivers you can exchange them up to V2 for free. The differences are:

- lower dropout voltage so that 5A 1.8V diodes can be driven with a 5V supply
- input over-voltage protection for low range (up to 2A)
- up to 6A drive with proper heatsinking
- gold plated solder contacts

Nice!

I was asking myself, if it is possible to power up two (660nm) diodes with the same driver, and if it would be a good idea?
I was thinking to put them in series (as I'm already doing that with power LEDs), so if one diode die one day there won't be double current on the other (current limiting driver...)

Seriously... This happened to me here.

What is the price?

FlexMod 1 Laser Modulator Circuit ($35 ea)

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Originally Posted by Admin

Seriously... This happened to me here.

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Haha worked as intended :)

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I was asking myself, if it is possible to power up two (660nm) diodes with the same driver, and if it would be a good idea?

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Hi, I'll post here what I posted in the V1 thread:

Hi, yes you can run many diodes of the same type from one driver, just stay within the current limitations of the driver (6A max)

Each diode is slightly different, so to even out the current draw between the diodes when they are in parallel, you should put a (thick) metal film resistor in series with each diode. This is true for driving parallel diodes no matter which driver you use.

Let's say you are making a super red and want to use as many red diodes as possible, and you want the max current to be 300mA to each diode, and the lasing threshold is 75mA. Choose a resistor so that it drops about 10% of the diode voltage at the idle current, or 0.3V at 75mA: 4 ohms. Then calculate its voltage drop and power disipation at full power: 4 ohms*300mA = 1.2V; 1.2V*300mA= 0.36W

So, for an array of open can diodes you should use 4 ohm, 1/2W or 1W resistors in series with each diode. Maximum number of diodes on one driver is 8A/300mA = 25 diodes.

Minimum power supply voltage for the driver would be 3V (diode voltage) + 1.2V (resistor voltage) + 2.0V (Driver requirement when delivering 8A (0.25V per amp)) = 6.2V. If you are only driving 2 diodes in parallel then a supply voltage of 5V is fine.

Finally, your diodes should be of the same make and model, and thermally coupled so they stay close to the same temperature, and electrically isolated. They should be connected to the same size heatsink block and with the same length and type of wire.

Typically if a red diode dies, it dies of optical failure and so will maintain virtually the same output voltage drop, saving the other diode it he pair. However if it fails open circuit via some mechanical abuse (I have never seen this happen after a diode was installed in a mount, but have seen it happen AS a diode was being installed, so test!) then the other diode will take double the current.

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Originally Posted by drlava

Haha worked as intended :)

Hi, I'll post here what I posted in the V1 thread:

Hi, yes you can run many diodes of the same type from one driver, just stay within the current limitations of the driver (8A max)

Each diode is slightly different, so to even out the current draw between the diodes when they are in parallel, you should put a (thick) metal film resistor in series with each diode. This is true for driving parallel diodes no matter which driver you use.

Let's say you are making a super red and want to use as many red diodes as possible, and you want the max current to be 300mA to each diode, and the lasing threshold is 75mA. Choose a resistor so that it drops about 10% of the diode voltage at the idle current, or 0.3V at 75mA: 4 ohms. Then calculate its voltage drop and power disipation at full power: 4 ohms*300mA = 1.2V; 1.2V*300mA= 0.36W

So, for an array of open can diodes you should use 4 ohm, 1/2W or 1W resistors in series with each diode. Maximum number of diodes on one driver is 8A/300mA = 25 diodes.

Minimum power supply voltage for the driver would be 3V (diode voltage) + 1.2V (resistor voltage) + 2.0V (Driver requirement when delivering 8A (0.25V per amp)) = 6.2V. If you are only driving 2 diodes in parallel then a supply voltage of 5V is fine.

Finally, your diodes should be of the same make and model, and thermally coupled so they stay close to the same temperature, and electrically isolated. They should be connected to the same size heatsink block and with the same length and type of wire.

Typically if a red diode dies, it dies of optical failure and so will maintain virtually the same output voltage drop, saving the other diode it he pair. However if it fails open circuit via some mechanical abuse (I have never seen this happen after a diode was installed in a mount, but have seen it happen AS a diode was being installed, so test!) then the other diode will take double the current.

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or you could buy two drivers:D

I was wondering the same thing. But it sound like the $35 extra would be worth it.

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Originally Posted by drlava

Hi, I'll post here what I posted in the V1 thread:

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Oh, I should have re-read the V1 thread, I wasn't remember me that :D

So ok for the parallel mode. But what's about putting the diodes in series? This will correct the diodes irregularities (at least for the current, not for the different efficiency of each diode but I think that's not very noticeable in use), and protect the others diodes if one gets shorted.

Of course it requires an input voltage to the driver at least equal to the sum of the dropout voltages of all the diodes in the circuit, plus a little extra voltage for the circuit operations... I don't know if the driver is ok for that. And I don't know too, if there's modulation slowdown or other problems, when drived in series?

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Originally Posted by Laserman532

or you could buy two drivers:D

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Originally Posted by DjDevNull

I was wondering the same thing. But it sound like the $35 extra would be worth it.

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I'll be fair, I'll let some drivers for the other members :D (otherwise I'll need at least 8 drivers!)

I'll give it a try and let you know..

have made an order of one of these driver circuits for trying like 2 weeks ago still waiting for it :(

Last I heard was a new batch is going out Monday,

Got mine.. Thanks DL

lava.. im interested in the "in series" experiment as well... please post results if you get any

Got mine! Looks great! Can't wait to try it out.
Thanks!
Adam

I just ordered two. hope they arrive soon.. I can't wait to get my open can red fired up! :)

well mine arrived today

did you guys get heatsinks with the drivers?

FlexMod2 with ndrew2505's lpc815 adjusted to 330ma.
I don't have a power meter, but when it fired up, I looked like this -->:D
Beam enhancement via Camel Light. I wish I had 10 of these!
-Mike

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Originally Posted by mikkojay

FlexMod2 with ndrew2505's lpc815 adjusted to 330ma.
I don't have a power meter, but when it fired up, I looked like this -->:D
Beam enhancement via Camel Light. I wish I had 10 of these!
-Mike

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cant you run the 815 up to about 450ma?:D:D:D:D:D:D:D:D:D:D

Do I hear 455? Woo Hoo!
Naw, this is my first one so I thought I'd keep it sane for a while.

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Originally Posted by mikkojay

Do I hear 455? Woo Hoo!
Naw, this is my first one so I thought I'd keep it sane for a while.

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I know those lasers are insane - I idle mine at 365ma and average 210mw:)

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Originally Posted by Lasernerd

well mine arrived today

did you guys get heatsinks with the drivers?

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Nope... Though he said he will send one for each driver.

Pat and Mike:

DZ is running a burn-in test on an open can red diode right now... (not sure if it's the 815 you got from ndrew2505 or not though) He's driving it at an utterly insane 550 ma! And the damn thing won't die! I'll PM him and see if I can get him to post in this thread... (And yeah, he's using the Flex-Mod 2 driver.)

Adam

Sadly, the test diode died. Good thing is that I know why. I had about 4 lasers pointed to a black heat sink while testing them all. One of them, a maxymodule, was clamped to a heat sink with a large metal clamp. I moved it to test it's power, as I moved it, the beam from the 250mW one hit the side and instantly dropped to almost no output. Oh well, have to start over, this time I'll have to be a bit more safe about it. I'm asuming that the more output you have from these guys, the more suseptable they are to failing from back reflection.

Regarding the 550mA reading I had. When I measured that, it was with Pangolin's abstract generator running. It would seem that somewhere while outputing an abstract, the beam is turned off, then back on (at least, this is what I suspect). Later that day, I decided to unhook from Pangolin and throw a solid 5V from a 7805 to the modulation in put, when I checked the output power, it was 310mW! Not 250mW I was reading when connected to Pangolin. I turned the power back down to 250mW, but didn't check the current then. Now this thing had run for several hours with a current reading of 550mA, which is amazing to me....

Just out of interest, what is the difference between these boards and the die4drive boards?

Hey DZ,
Out of curiosity, what kind of heat output have you noticed with these guys? I am trying to get an idea of what the heat sink requirements will be, especially as you pump em up. Is it less/more/same as a 405nm running at 100ma? I have 2 of the z-bolt heat sinks, but I was thinking about trying to cobble a couple cylindrical ones on the lathe out of a chunk of aluminum bar stock.
Keep on with the updates- very interesting!
Thanks, Mike

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Originally Posted by DZ

..when I checked the output power, it was 310mW! [..]

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Did you use an acrylic or glass lens for collimation?

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Out of curiosity, what kind of heat output have you noticed with these guys?

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Really not much at all. I've got it fairly well heat sinked, it's in an old scanpro mount.:rolleyes: Touching the mount or the aixiz module, neither was warm to the touch. The heat sink on the flexmod was rather warm though.

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Did you use an acrylic or glass lens for collimation?

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I *think* it's a glass lens. Here's a pic of the setup, it's not like the typical lenses I see with the aixiz modules so I'm guessing it's a glass one?

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Originally Posted by dave

Just out of interest, what is the difference between these boards and the die4drive boards?

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Hmm, from a quick look at the website it looks like the differences (other than the way you mount them) include:
-Wider input voltage range
-Higher current drive capability
-Higher power capability
-Adjustable speed
-Protection from input over-voltage on 0-1A range
-11-turn pots instead of single-turn for precise adjustment

DZ, yep that's a multi-element glass aixiz lens there.

Question:

I'm setting up a flex for a dual LOC red, but the gain pot doesn't seem to do anything. It is set up exactly like my other one, which works fine. The other one is set for 20ma 0bias and 230ma with +5 on the mod line.

I can adjust the 0bias no problem but when i put +5 on the mod line, it does nothing--just stays at 20ma and no amount of adjusting on the gain pot does anything.

Best i can tell, my soldering is good. Any Ideas or test points?

Thanks,

doug

Double check your range-setting solder blob first. Then touch your hot soldering pencil to the solder joints of the resistors next to it and the 102 resistor on the other side of the gain pot, and the gain pot joints. Should take care of it, if not send me a PM for my address.

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Originally Posted by mophead

Best i can tell, my soldering is good.

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Having a closer look, my soldering is crap.

Cold joint on the blob. Well flux-me-running.....

thanks fer the help.

you're not the first to do that!

glad it worked out.