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My new DIY red laser

alessnilsen

alessnilsen

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I used LM337, the negative version.

This is the circuit that I used:

lm337.jpg


It don't work for me. I also tried this one:

lm337-2.jpg


Didn't work too. For R1 I used 5 Ohms, so must give me 300mA, using the battery I got 274mA, but using a 15V power supply the current was more than 500mA (my multimeter can't measure).

I think is better to use my LM338, its simiar to LM317, but is a 5A regulator instead of 1,5A. In this case, I'll use this:

lm338.jpg
 





Cube777

Cube777

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The LM338 should work great if you use it in that circuit (used that driver multiple times), although I would recommend that you use fixed resistors with high power ratings, I busted a M140 because i used a pot that couldn't handle the current.
 
alessnilsen

alessnilsen

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YES! LM338 Works like a charm! Using a 15V power supply, 5.6 Ohms resistor for R1 must give me 223mA, using a 10 Ohms resistor as load, I got 220,3mA! For the first time I make a driver that works! :wave:

I busted a M140 because i used a pot that couldn't handle the current.
Click to expand...

I know, remember this?

About the other lasers, my driver killed all , I was using a trimpot to set the maximum current, the trimpot gets hot and more hot, increasing the current without my permission!!!
Click to expand...

On the shop have a potentiometer of 4W 200 Ohms, I think it can handle the current, since I was using 3W resistors. Since this driver will be only for tests, is interesting to have a potentiometer.
 
alessnilsen

alessnilsen

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Maybe. One LM337 I used in my first red laser, same thing happens to it, the voltage of the battery is quite stable, so isn't a big problem.
But this LM337 is new, same thing happens. I don't know why.
 
alessnilsen

alessnilsen

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ALL my LD's were now DEAD!! :cryyy::cryyy::cryyy: :wtf:

ALL!

Today I bought 3 DVD burners, two was the same model, two open can and one frame type. I reguled my driver to send 400mA of power to the LD. I used my 7.4V battery. I played all the afternoom with my laser until the battery goes down.

Since my driver works well, I think I can use any power supply with my driver, I can't!! :cryyy: First, I used a 15V power supply. At the moment that I pluged the power supply, the LD output goes down, now was a LED, DEAD!
I took this LD off and put the frame type one, since all was from 20X DVD burners, I used 400mA too, but now, a 12V power supply. I connected the power supply to the driver, and, the laser worked, I disconnected the power supply, when I reconnected the power supply th the driver, same thing! A LED! DEAD!!!!

:cryyy: :gun:

A total of 11 DVD burners was disassembled! ALL the LD's dead! I don't know what to do!
 
The Lightning Stalker

The Lightning Stalker

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That is sad. The diode might be getting a surge when the power is first connected. It's hard to test for
something like that without an oscilloscope and pulse generator. The only thing I might suggest is to use
a bigger capacitor across the diode. Just make absolutely sure it is discharged before putting the diode in
circuit.
 
alessnilsen

alessnilsen

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Yes. Very sad! :(

When I get other LD, I'll test with the large capacitor, since I was using the circuit of the datasheet and they don't have the capacitor.

Thanks.
 
The Lightning Stalker

The Lightning Stalker

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Well, if there wasn't any capacitor at all, there is the failure mode right there. The regulator overshoots and bang goes the diode. Use solid tantalum if you can get it, at least 10μF
 
alessnilsen

alessnilsen

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Solid tantalum? Maybe I have some here.

Other question, I got some IR LD's from the DVD burner, what can I do with it?

Thanks!
 
The Lightning Stalker

The Lightning Stalker

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Some of the IR can do 4-500mA with the right heatsinking and make good burners. They are more
dangerous though since the beam is invisible but can still blind you.
 
alessnilsen

alessnilsen

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Good! I'll use a 10uF 25V.

Other qustion. I tried to use the objective lens from the DVD burner to collimate the beam, but the collimated "dot" have a strange look:

laser.blog.00059.JPG


This happens with all the objective lenses that I tested! Why this happens?

This is my last project that died due to the missing 10uF cap:

laser.blog.00057.JPG


The heatsink with "Gigabyte" is the driver, the plane heatsink is the LD, the other diy deatsink is the focus adjust and the block close to the LD's heatsink is the objective lens/focus system.

laser.blog.00058.JPG


This is all the parts working. The focus system is very poor, If I put the laser in a plane surface and focus it, it will still focused when I leave it leveled, but if I point the laser to the ceiling or to the ground, the focus is lost, gravity's law!
 
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