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Lava Micro FlexDrive Driver (lavadrive2) fits pens

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drlava

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Re: Lava Micro FlexDrive Driver (lavadrive2) fits

woop said:
hey drlava, is the ground pin on the diode at ground potential?
ie, are the two ground pins connected together?
Hi, yes the ground pin on the diode is at power ground potential.  You can use the case-connected diode ground as the ground for the circuit.

F1SportsFan said:
I was looking at one of these drivers to run a Blu Ray LD, powered by a single 10440 cell (3.6V 305mA).  Do you see any problems with that set-up?  I am not sure if that will be enough current to run the LD for very long.  

If everything sounds good, definitely count me in!  Those circuits look great!  :)
Yep will be just fine!  Looks like Igor covered that one, thanks! :)

EDIT: the order page is now up, see the first post for the order page link!
 



Glaserfan

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Re: Lava Micro FlexDrive Driver (lavadrive2) fits

Drlava.. one thing I didnt ask in my PM... I see that 125 mA with a 3v to 6v boost as about max.. how about 420ma with a 3v battery and a red open can diode?:) I am hoping to build a 250mw-300mw burner(depending on the module/lens) with a Dorcy Jr..
 

drlava

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Re: Lava Micro FlexDrive Driver (lavadrive2) fits

Glaserfan said:
Drlava.. one thing I didnt ask in my PM... I see that 125 mA with a 3v to 6v boost as about max.. how about 420ma with a 3v battery and a red open can diode?:) I am hoping to build a 250mw-300mw burner(depending on the module/lens) with a Dorcy Jr..
Hi, yes it handles that just fine. I tested a 3V battery with an open can to 500mA and the driver didn't break a sweat on that. What I meant as about max was as far as boost voltage goes.. It can boost to 6.2V at 150mA + but as you get over 6.2V, the efficiency drops quite a bit. Considering 405nm diodes are usually 5V or under it shouldn't be an issue.

Here's a photo of a kryton V1 barrel install with a diode to drom the 6V of the bateries to 5.5V:
 

Skram0

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Re: Lava Micro FlexDrive Driver (lavadrive2) fits

Any way to get it to go under 32mA? Say if you want 30mA, can you mod one of the sm resistors or would it just be best to add a little resistance on the output?
 

drlava

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Re: Lava Micro FlexDrive Driver (lavadrive2) fits

Skram0 said:
Any way to get it to go under 32mA? Say if you want 30mA, can you mod one of the sm resistors or would it just be best to add a little resistance on the output?
Hi, adding resistance to the output would not affect the current (it's a current source) but changing the 2K resistor to a higher value will allow for lower limits beyond 32mA.
 

VW

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Re: Lava Micro FlexDrive Driver (lavadrive2) fits

I'm seriously interested in picking one of these up, I can't see your pictures...
 

IgorT

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Re: Lava Micro FlexDrive Driver (lavadrive2) fits

drlava said:
[quote author=Skram0 link=1209418066/30#35 date=1210181711]Any way to get it to go under 32mA? Say if you want 30mA, can you mod one of the sm resistors or would it just be best to add a little resistance on the output?
Hi, adding resistance to the output would not affect the current (it's a current source) but changing the 2K resistor to a higher value will allow for lower limits beyond 32mA.[/quote]

Or if someone is uncomfortable with changing SMD resistors, they could put a resistor in parallel with the load, like we do with the AMC.

With such low currents, it doesn't matter if you waste a few mA. I would prefer to adjust it properly, but it is an option.
 

jayrob

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Re: Lava Micro FlexDrive Driver (lavadrive2) fits

drlava, lets say a guy wanted to build a red laser with the FlexDriver, and wanted to use 2 X 3.0 volt lithium primaries and a silicon diode like in your picture...

Would there be any heat issues to the driver because of the extra voltage? I like the idea of using the CR123's because they could sit for a long time without loosing charge or leaking.
Jay
 

drlava

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Re: Lava Micro FlexDrive Driver (lavadrive2) fits

jayrob said:
drlava, lets say a guy wanted to build a red laser with the FlexDriver, and wanted to use 2 X 3.0 volt lithium primaries and a silicon diode like in your picture...

Would there be any heat issues to the driver because of the extra voltage? I like the idea of using the CR123's because they could sit for a long time without loosing charge or leaking.
Jay
Hi, there wouldn't be any heat issues with the driver, because it is a switching driver with good efficiency. Here are some basic calculations:

Let's say that you use 2 3V lithium primaries with the In4001 drop diode as in the photo. You want to use an open can diode at 400mA. Assuming 85% driver efficiency and a laser diode drop of 3.1V,

Laser Diode power dissipation: 1.24W
Driver power disipation: 219mW
Driver current draw from batteries: 275mA
1N4001 diode dissipation: 192mW
Total driver related power dissipation: 411mW
Net power dissipation requirement for heatsink: 1.65W
Estimated battery runtime: 4.1 Hours with no dimming

The dissipation figures and runtime get even better when you use a single li-ion rechargeable such as a 17670 because the 1n4001 isn't needed.

Compare this with another common linear regulator driver:
Laser Diode power dissipation: 1.24W
Driver power dissipation: 1.16W
Driver current draw from batteries: 400mA
Net power dissipation requirement for heatsink: 2.4W
Estimated battery runtime: 2 hours before dimming due to dropout voltage
 

jayrob

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Re: Lava Micro FlexDrive Driver (lavadrive2) fits

Man that's straight up got to be the best driver possible! :D

Thanks for the information. And for making your awesome FlexDrivers available! Is the plan to keep these in production?
Jay
 

Dark_Horse

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Re: Lava Micro FlexDrive Driver (lavadrive2) fits

Good morning,
Probably a fairly basic question, but here goes: I would like to use your driver to run a "open-can" diode @ 400 mA, using a single 14500 battery-900mAh (AA-size lithium), am I risking the max-discharge rate for this battery? (using duty-cycles as advised).
Dark Horse
 

thejunkmonger

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Re: Lava Micro FlexDrive Driver (lavadrive2) fits

I was thinking if there was a way to integrate into this design a circuit that would flash the laser when your secondary cr123's got to 3 v??. or something so we could know when to charge them without destroying them.
 

drlava

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Re: Lava Micro FlexDrive Driver (lavadrive2) fits

Dark_Horse said:
Good morning,
Probably a fairly basic question, but here goes: I would like to use your driver to run a "open-can" diode @ 400 mA, using a single 14500 battery-900mAh (AA-size lithium), am I risking the max-discharge rate for this battery? (using duty-cycles as advised).
Dark Horse
Hi, Probably, yes. Whether the battery could handle it depends on the manufacturer and internal resistance, but it would most likely be fine for brief (non-continuous) operation.
 

IgorT

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Re: Lava Micro FlexDrive Driver (lavadrive2) fits

With a 14500 powering an open can through this driver, the current draw on the battery would be lower or the same as the current through the LD.

I'm using protected 14500s (Ultrafire and Trustfire) in a CREE LED modded 1xAA flashlight, where the current draw is around 1.35A. I've had no problems so far, and i've left it on for 10-20 minutes at a time, several times, to see how hot it would get. It gets warm with the rest of the flashlight, but the protection never cut in.

Since their actual capacity is not really 900mAh, but closer to 600mAh, what i'm doing is at, or slightly above the limit for continuous discharge (2C), but an open can, i don't see why that would be dangerous in any way.

If you want to be safe, just buy the protected ones.
 

Dark_Horse

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Re: Lava Micro FlexDrive Driver (lavadrive2) fits

Thanks guys,
I have already ordered a couple of 'low-range" drivers for the "X-Box" diodes I have coming in, I will have to order a high-range one as well now.
I am really looking forward to this driver Dr. Lava, it looks like you have done a great job!! ;D
Dark Horse
 
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