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ArcticMyst Security by Avery

A little help with this

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Feb 5, 2008
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Rechargable lithium ion batteries.

Ofcourse, they'd neccesitate the use of a flashlight body to hold it all together since I didn't see any square looking, or desktop friendly lithium ions around.

But they are rechargable, last brutally long, charge in no time, excellent current capabilities.
 





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And i would like to get around 250mA for 150mW so V=I/R
R=5

The formula is V = IR ! (or I = V/R, or R = V/I) Im guessing it was just a typo though, as you calculated the resistance correctly? :beer:
 
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I dont know what im going to use as host but i think ill just put it inside a flashlight or just a little box/case.

And yeah the V=I/R was a typo, forgot to edit it

OH and how do i short the driver? i just read that if i dont there is a chance it might die
 
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luccax

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I suggest a ceramic capacitor, they won't burn your diode if you don't short the leads before running it. They have a very low charge.


By the way: Great forum name you got there
 
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What you probably mean is,

Shorting the output capacitor.

It's as simple as crossing the leads that are supposed to go to the diode for a second.

This is to discharge any residual charge left in the capacitor, and make it safe to connect your diode to the output.
 
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You don't need an output capacitor, and it can even hurt your circuit as it'll affect your circuit as a constant current source. That diagram is very old and the idea at the time was that you'd be filtering transients at the output; however, the voltage regulator does an excellent job of rejecting problematic voltages/currents. If you put the capacitor anywhere, put it before the voltage regulator.
 
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luccax

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What you probably mean is,

Shorting the output capacitor.

It's as simple as crossing the leads that are supposed to go to the diode for a second.

This is to discharge any residual charge left in the capacitor, and make it safe to connect your diode to the output.

exactly, thats what I meant to say, mabe english fail.

No need to do that with ceramic capacitors
 
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If it's a capacitor in any way,

Yes, you need to do that. If you didn't, it wouldn't a capacitor.

But I'd go with the other advice of even ditching the capacitor altogether if it's a problem.
 

luccax

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their capacitance is too small to burn a diode. I bet all my m140s, they wont burn
 
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You can never be too careful. Better safe than buying another diode.

Besides, I've seen some really high capacitance small ceramic SMD caps, like 10uF, two in parallel was all I needed in some switching driver design for the output cap.
 
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Jul 22, 2012
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@OP What lens and module are you going to be using? And if you need more ideas on easy to build laser drivers here is a nice PDF with some (see attachment). The LM2941 driver in the PDF works great with two Li-Ions, running my lpc-826 at 510mA with 7.2V!!!
 

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Go to DTR's site and buy the lens that says "635nm-660nm AR Coated Three Element Glass Lens". If you are sure that the module you are using is an aixiz module then this lens will work great!
 




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