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prokrypt

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Hi! I've been reading a few threads here and finally decided to register.

I paid for the 16x DVD laser diode, and I'm just trying to find some suitable way to power it. I plan on putting the whole thing in a 1AA flashlight, so my choices of batteries are either AA or 14500 Li-Ions.

Measurements on the existing flashlight board gave ~4.5v and 300~600mA depending on input voltage. Any ideas on how to piggyback another circuit on it to limit voltage/current?

I have also thought about throwing out the board and building my own circuit to run it on 14500 Li-Ion. However, I have never done anything past soldering simple components together.

Will this SMD chip work?
Code:
mouser.com/search/ProductDetail.aspx?R=AP139-25WL-7virtualkey62110000virtualkey621-AP139-25WL-7
Thanks! =D
 



laserrod

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Re: Will this work for powering a laser diode?

Thats a voltage reg.
I would use a current reg instead.
If you do use a volt reg. then U have to pic the right current series resistor in the
<1 ohm range in the .01 increments.
I think the LD needs 2.8 volts so take your reg voltage minus 2.8 then say .3 amp laser current MAX

V/A=R

I am going with a LM317 in current limit mode then I can use any voltage.

Cheers
DGM [smiley=beer.gif]
 

wilheldp

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Re: Will this work for powering a laser diode?

prokrypt said:
I plan on putting the whole thing in a 1AA flashlight, so my choices of batteries are either AA or 14500 Li-Ions.
You're only going to power this thing with 1.5V?
 

prokrypt

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Re: Will this work for powering a laser diode?

wilheldp said:
[quote author=prokrypt link=1187988356/0#0 date=1187988356]I plan on putting the whole thing in a 1AA flashlight, so my choices of batteries are either AA or 14500 Li-Ions.
You're only going to power this thing with 1.5V?[/quote]

If I'm going to be using only 1AA, then of course I'm gonna keep the boost circuit that's already in the flashlight. The problem that I have now is limiting the current to the laser diode. I don't think I can use the LM317 because the voltage dropped may be too high.
 

Gazoo

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Re: Will this work for powering a laser diode?

I'm curious, which flashlight exactly do you have. And with your measurement of 300~600mA, I assume it was measured with the LED that came in the flashlight? I have been thinking about trying out the Dorcy 1 AA flashlight.

http://www.dorcy.com/products.aspx?p=414253
 

prokrypt

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Re: Will this work for powering a laser diode?

Gazoo said:
I'm curious, which flashlight exactly do you have. And with your measurement of 300~600mA, I assume it was measured with the LED that came in the flashlight? I have been thinking about trying out the Dorcy 1 AA flashlight.
The light I'm using is DX's famous MTE SSC P4 light, loved by many. However, I think its output sucks, so I'm going to shove a high-powered laser into it  ;D
And uh... my measurements were made by shorting the multimeter on the output with no LED. Is that a Bad Thing?
 

Gazoo

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Re: Will this work for powering a laser diode?

Oh...that one... ;D I was looking at it earlier but they are out of stock. It is a nice little light...5 modes and all.

I don't know if measuring current the way you did is bad or not. I am not familiar with boost circuits. But all you would need to limit current would be a 1/2 watt resistor. I have no idea how many ohms. When you hook the diode up to it make sure you have a resistor so you don't blow the diode. Of course when you hook a diode up, voltage and current will drop.

I think these little lights will be easy to mod. I have the real small aixiz modules and they will fit in almost anything.
 

chimo

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Re: Will this work for powering a laser diode?

prokrypt said:
[quote author=wilheldp link=1187988356/0#2 date=1188006003][quote author=prokrypt link=1187988356/0#0 date=1187988356]I plan on putting the whole thing in a 1AA flashlight, so my choices of batteries are either AA or 14500 Li-Ions.
You're only going to power this thing with 1.5V?[/quote]

If I'm going to be using only 1AA, then of course I'm gonna keep the boost circuit that's already in the flashlight. The problem that I have now is limiting the current to the laser diode. I don't think I can use the LM317 because the voltage dropped may be too high.[/quote]

You could use a Low Drop Out (LDO) regulator substitute for the LM317. The NCP3335A from ONSemi has a 230mV dropout and the MC33269 has about a 1V dropout. If it is a real 1W driver in the Dorcy it was boosting the voltage to about 3.3 V at about 300mA. The LD will be looking for about 1V less than the LED was in the Dorcy.

Paul
 

Gazoo

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Re: Will this work for powering a laser diode?

If those are the specs, then putting a silicon diode in series with the LD should make it about perfect.
 

prokrypt

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Re: Will this work for powering a laser diode?

Yay, I received my chip samples today!
- LP38690DT LDO Voltage Regulator (2.5v, ~1A?)
- LP3878MR Adjustable Voltage Regulator (1.0-5.5v, 800mA)

I tried out the 2-pin 2.5v regulator on a regular red led (heh, Overdrive!) and measured around 45mA current draw. The led didn't burn out :]. I couldn't measure the max current draw (by shorting out multimeter on output) because it had some sort of short circuit protection (nice!).

Will the LD suck more than its rated current if it's run at its rated voltage (with 2% accuracy)?

The teeny 8-pin adjustable voltage regulators are still in their tubes, and will stay there until I get a smaller soldering iron that does NOT fry every chip I use it on.
Oh yeah, can any adjustable voltage regulator be turned into a current regulator, or only certain chips?

More updates to come when I get access to a suitable soldering iron and when my LD comes :]
 

prokrypt

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Re: Will this work for powering a laser diode?

I got my 5mw laser module and flashlight today! So far, I have gotten the circuit up, but I'm still experimenting with the placement of the module in the flashlight.
For the circuit, I'm hoping that the laser won't eat more than it can chew with my regulated 2.5v (~600mA max). Pictures below :]

I hope I get my laser diode tomorrow!
 

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prokrypt

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Re: Will this work for powering a laser diode?

another picture

and uh.. there's no real heat sink. it's just a washer badly soldered (it's my first time doing something like this) to the module :]
 

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Daedal

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VERY nice! Considering it's your first rig, this is a very nice setup :)

Let us know how the new diode turns out ;)

--DDL
 

BlueFusion

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eheww... measuring current can only be done with a load in place. a direct measurement through the multimeter will likely burn out your multimeter and driver board. it will also not give an accurate reading. nice that it works tho...
 

Things

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man that module looks like mine too????hmmmm how long is it?
 

prokrypt

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Laser diode arrived today!

I tried my circuit and measured around 125mA going to the diode at almost exactly 2.5v. That measurement was probably not accurate because I put my meter on the 500mA range, and it's analog. I'm not sure what output wattage this is, but it burned the black lid of my laptop when focused. Smokey ::).
As of now, I'm using a 3.6v (4.0v when charged) Li-Ion battery to run the laser. Regular alkalines should work too, but I didn't have any new ones to test with. A used alkaline cell (~1.15v) didn't throw a bright a dot as the lithium ion cell, probably because it wasn't delivering enough current. The laser drew a bit less than 250mA from the Li-Ion (~3.8v), and more with the used alkaline (~1.15v) cell.

More info and pictures to come later on :]
 




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