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Help with laser build

Amply

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Alright so I have built a linear driver using a LM1085 voltage regulator and 2x 1 ohm resistors in parallel using a m140 2w laser diode being ran by 3x 3.7v 2500mAh 18650 (from panasonic). (also has a cool missile launch style rocker switch :D)

Here's kind of a picture of what i have so far.. It's not pretty... This shows the underside. Imgur: The most awesome images on the Internet

So i went to test it out for the first time today and I'm having some problems and hoped someone could help me solve them.

When i turned it on the diode lit up but it was very weak? it shot out a dot at what it was hitting very focused in the center but a blue ring on the outside? like a target sign and you could not see the actual beam even when it was pitch black in the room. The batteries were fully charged (brand new first time being used) So I'm lost as to what the problem could be.
 



diachi

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Batteries are in parallel too by the way

That's going to be part of your issue for a start. Linear supplies need an input voltage greater than the output voltage (Output voltage + dropout voltage). You're supplying 3.7-4.2V to the driver which needs to supply >4.5V. Try two of those Lithium batteries in series instead - that'll give you enough voltage. I'd also verify that the driver is working correctly using a test load - in order to avoid frying your diode with a driver that may not be working properly - always a good idea.

Once the driver has been verified to be working properly we can troubleshoot further if necessary.
 

Amply

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3 in series would be fine too? I want it to have some kind of run time
 

diachi

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3 in series would be fine too? I want it to have some kind of run time
Then you want to use 4 - two in series in parallel with two in series. Adding a third one in series just makes the whole thing less efficient and won't improve run time - the extra energy will be dissipated as heat at the regulator. Such is life with linear regulators.
 

Gadget

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No, the extra cells voltage would just be turned into heat in the regulator. A linear driver NEEDS two cells in series to drive an M140. If you need more runtime, you'll need a 2s2p cell configuration.

-G

(Oops...was typing this as diachi posted his)
 
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diachi

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No, the extra cells voltage would just be turned into heat in the regulator. A linear driver NEEDS two cells in series to drive an M140. If you need more runtime, you'll need a 2s2p cell configuration.

-G

(Oops...was typing this as diachi posted his)

Gotta be quicker next time! ;) :D

+rep
 

diachi

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Oh i was confused because of this http://laserpointerforums.com/f67/lm1085-diy-driver-62227.html
That's the driver I built.
Is there a chance that some of my components were damaged from me running it as 3x in parallel?

No - but always worth testing the driver is functioning properly before hooking up the diode.

Also could you draw up a example schematic I'm not understanding how you can have 2 series and 2 parallel being hooked up.

A better understanding of electronics may be good before you proceed - sounds like you don't have much experience with electronics if you're having trouble with that or you are misunderstanding us.

Put two cells in series in parallel with another two cells that are also in series.


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Amply

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omg it works!!! it caught my bathroom wood trim on fire though...
 




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