Flashlight drivers?

tsteele93 · Feb 19, 2012

So I'm new to this and trying to learn fast. Realizing that this hobby and flashlights are kind,of like cousin (or sibling) hobbies, I decided to check our flashlights.

I ordered a 7W Cree V-Shark light with 800mA current. Neat little light. Cheaply made, but 400 lumens in a small package with hi, Li and strobe.

My question is, could you just use the driver in this to power a laser build in the host?

I tried to search this but wasn't using the right terms...

EDIT: At first glance, THIS looks like the information I am looking for...

http://laserpointerforums.com/f67/c...ost-converters-cheap-445nm-drivers-59058.html

foulmist · Feb 19, 2012

tsteele93 said:
So I'm new to this and trying to learn fast. Realizing that this hobby and flashlights are kind,of like cousin (or sibling) hobbies, I decided to check our flashlights.

I ordered a 7W Cree V-Shark light with 800mA current. Neat little light. Cheaply made, but 400 lumens in a small package with hi, Li and strobe.

My question is, could you just use the driver in this to power a laser build in the host?

I tried to search this but wasn't using the right terms...

maybe if you hook the driver to a test load and see. or take a picture of it and post it here so we can see what it's about.

foulmist · Feb 19, 2012

BlahHead said:
Is there any reason why it won't work? (voltage, current...)

One thing I quite couldn't grasp is the concept of voltage. People seem to mention currents while driving their laser diodes but I don't think I encountered anyone mention volts. Why is that?

Thanks!

because we are using drivers with constant current rather than constant voltage.

changes of temperature affect the laser diode's forward voltage and thus increase/decrease the current. So if you are using constant voltage excess current will eventually kill the diode.

foulmist · Feb 19, 2012

BlahHead said:
Oh, now I understand.

Many thanks to you, buddy! +1

Could we share successful instances where a flashlight driver was used as a LD driver?

I dug through Google and found out that the NJG-18 driver could be used both as flashlight and laser diode drivers.

It would be cool to have a 5-mode driver with high, med, low, strobe, and SOS mode. haha

Cheers!

yeah there are lots of drivers which use constant current to drive LEDs. Search through the forum there are some in the drivers section

:beer:

GAtkins · Feb 19, 2012

18V 5W Cree Circuit Board for Flashlights (16.8mm*5.5mm) [LEDBRD] - $4.99 : Cajunlasers Store

18V 5W Cree Circuit Board for Flashlights (16.8mm*5.5mm) - Free Shipping - DealExtreme

Glenn

tsteele93 · Feb 19, 2012

GAtkins said:
18V 5W Cree Circuit Board for Flashlights (16.8mm*5.5mm) [LEDBRD] - $4.99 : Cajunlasers Store

18V 5W Cree Circuit Board for Flashlights (16.8mm*5.5mm) - Free Shipping - DealExtreme

Glenn

Here was my thinking...

I just ordered a small flashlight for a laser build. I see in the specs that it has an 800mW current driver. It already uses an 18650 so if I could use the driver that came with it, the build could be greatly simplified. I just need to choose a diode that can take 800mA. (445 I suppose)

But what voltage do the diodes need to see?

I assume since constant current drivers are the way to go with lasers, that the voltage can vary a bit - but what are the ranges and do different diodes have different requirements?

I've been trying to learn fast, but I haven't stumbled on anything that addresses this yet. I'm sure it is in Sam's FAQ. I'll just have to dig for it.

GAtkins · Feb 19, 2012

I am new at this too, but my understanding is that it is totally dependent on the driver. For example, the driver above's specs are as follows:

1*Cree 5W regulated power output
- Output current: 1.25A
- 16.8mm diameter base, 5.5mm overall depth
- Voltage: 3V-18V
- Fully regulated circuit design

If my reading of this is correct, you feed that thing anywhere from 3 to 18V, allowing for the voltage drop of the circuit (maybe use 2x 16340's, according to Cajun) and it will output a regulated 1.25A, which would be midrange specs on a 445. Some of them are being driven at 1.8A.

Based on my personal experience, I am getting 1.50W out of a DTR 445 driven at 1.62A with Moh's driver and with a regular 3 element glass lens and 1.95W us a G2 lens. According to Cajun's description page, he got 1.1W using the above Cree driver at 1.25A. My diode sounds more efficient than his. I any case, you should be able to easily get 1W out of this driver I would think.

Anybody else?

Glenn

tsteele93 · Feb 19, 2012

GAtkins said:
I am new at this too, but my understanding is that it is totally dependent on the driver. For example, the driver above's specs are as follows:

1*Cree 5W regulated power output
- Output current: 1.25A
- 16.8mm diameter base, 5.5mm overall depth
- Voltage: 3V-18V
- Fully regulated circuit design

If my reading of this is correct, you feed that thing anywhere from 3 to 18V, allowing for the voltage drop of the circuit (maybe use 2x 16340's, according to Cajun) and it will output a regulated 1.25A, which would be midrange specs on a 445. Some of them are being driven at 1.8A.

Based on my personal experience, I am getting 1.50W out of a DTR 445 driven at 1.62A with Moh's driver and with a regular 3 element glass lens and 1.95W us a G2 lens. According to Cajun's description page, he got 1.1W using the above Cree driver at 1.25A. My diode sounds more efficient than his. I any case, you should be able to easily get 1W out of this driver I would think.

Anybody else?

Glenn

Another member PM'd me to point out that these drivers may be poor quality and have current spikes. So not a good idea for a high current build near the limit of the diode.

But for a lower power build, it might be worth it to get some of the effects, like low power and strobe that a lot of the flashlights come with?

Might be worth trying on some cheap reds?

EDIT: I noticed the following comment on your driver...

Other Thoughts:
The top of the IC is polished, but I think, this is came with AX2002 (the driver board color is red).

It's a one mode, good efficiency switching driver. The diode is SS34 (3A current limit).

If you change the sense resistor to 0.125 ohm, the output current is changed to 2A (the AX2002 has 0.25V feedback voltage).

I use this driver with two serial connected 18650 battery.

That adds an interesting angle to it as well. A simple resistor change could let you tailor it to your liking.

GAtkins · Feb 19, 2012

@tsteele93,

which cheap reds could be used?

Glenn

tsteele93 · Feb 19, 2012

GAtkins said:
@tsteele93,

which cheap reds could be used?

Glenn

I'm assuming LPC-826's... Let me check. (not the 1.25 a board, I'm saying a lower current board for experimenting with a red) The LPC-815 might even be a better place to start.

We could use the help of more experienced members here. I'm sure there must be a reason why Ben, RHD, dr. lava and so many others are designing their own drivers, so I might just be spinning my wheels here. I'm just curious as to why this isn't a viable way to drive a laser pointer, if it isn't.

This driver is super inexpensive on DX

3.6V~16V 925mA Constant Current LED Driver Board for Cree and SSC LEDs (4-pack) - Free Shipping - DealExtreme

foulmist · Feb 19, 2012

If you want to use a single battery operation for 445nm diode and bluray, you need boost or boost buck driver. Most flashlights use regulated buck drivers or some non regulated which are not current steady

you can use buck but you need at least 2 batteries for full current output when diode's forward voltage is above the battery's voltage + drivers drop voltage.

that's why there are other drivers developed... I am currently finishing mine as well - a boost/buck driver capable of 2A

and guys these things have been discussed widely here please do some research first

:beer:

tsteele93 · Feb 19, 2012

foulmist said:
If you want to use a single battery operation for 445nm diode and bluray, you need boost or boost buck driver. Most flashlights use regulated buck drivers or some non regulated which are not current steady

you can use buck but you need at least 2 batteries for full current output when diode's forward voltage is above the battery's voltage + drivers drop voltage.

that's why there are other drivers developed... I am currently finishing mine as well - a boost/buck driver capable of 2A

and guys these things have been discussed widely here please do some research first :beer:

I searched with no luck. Search in forums is really not consistent.

Hiemal · Feb 19, 2012

http://laserpointerforums.com/f67/how-laser-diode-drivers-work-explanatory-thread-71513.html

Fretwrecker94 · Feb 19, 2012

tsteele93 said:
Here was my thinking...

I just ordered a small flashlight for a laser build. I see in the specs that it has an 800mW current driver. It already uses an 18650 so if I could use the driver that came with it, the build could be greatly simplified. I just need to choose a diode that can take 800mA. (445 I suppose)

But what voltage do the diodes need to see?

I assume since constant current drivers are the way to go with lasers, that the voltage can vary a bit - but what are the ranges and do different diodes have different requirements?

I've been trying to learn fast, but I haven't stumbled on anything that addresses this yet. I'm sure it is in Sam's FAQ. I'll just have to dig for it.

Build a test load, test the driver, if the current appears to be safe for your diode use it. The voltage draw will only change as the diode's need changes. They're current hungry, not voltage hungry. Which is why we used constant current drivers.

Blord · Feb 19, 2012

tsteele93 said:
I searched with no luck. Search in forums is really not consistent.

http://laserpointerforums.com/f67/driver-mod-up-1-8amps-2x-3-7v-3-0v-cells-59336.html

tsteele93 · Feb 19, 2012

Blord said:
http://laserpointerforums.com/f67/driver-mod-up-1-8amps-2x-3-7v-3-0v-cells-59336.html

Ok, well I was searching for keywords flashlight and driver. Obviously not searching correctly... But I DID search and wasn't just throwing this out there.

Also, I'm trudging through Sam's page but finding it tough not to end up in a bunch of HeNe topics that don't apply to diodes.

Sorry.

Le Quack said:
http://laserpointerforums.com/f67/how-laser-diode-drivers-work-explanatory-thread-71513.html

I've read that, not sure if I'm too dense but it doesn't seem to help me much with understanding why a DX 325mA flashlight driver would, or wouldn't, drive a laser diode.

:beer:

Flashlight drivers?

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