Another power source thread BUT really different

[hroldan]

Hi there, been reading a lot here and there but can't clear some doubts. Yes, I tried building my own power source following tutorials using the LM317 power regulator to no luck ruining two lasers, yes, despite following the instructions found on diff sites. I also found other testimonials on people not having luck (yes, others did get lucky), not me.

So before ruining other lasers that took time to remove from DVD burners I will appreciate some help. I understand the laser needs specific voltage (V) and specific current (C, mha, etc). If the right power source is not provided, the laser gets hot and dies, and mostly because the laser will consume as much energy as it can gets, or whatever something like that, thus an specific power source with both values fixed is needed.

- Does a common adapter sold at radioshack would work? they can provide specific voltage (3, 5, 6, 7, 9) at specific currents (200mA, 300mA), because... If choose carefully I could get the voltage I'm aiming with the DIY power source, right?

- Does powering it from a USB computer power source work? because USB ports feed specific voltage and current, and USB 3.0 feed even more.

- Am I doomed at facing again, building another power source out of some voltage regulator? I will, I'm just researching all I can to avoid doing it wrong. I saw some tutorials measuring and taking apart regulators from some dvd boards.


I'm working on a DIY laser engraver, nope, buying online is not something easy as I don't live on the US, things not only take time to get to my door: burning lasers and stuff like that faces problems on shipping (most of times) so, I want to avoid ordering something just to wait and find out it's not allowed.

I will appreciate your help! thanks in advance.

. . . . . . . . .

Background: (yes I tried)
So, I know powering the laser directly with batteries will rarely work (it will mostly burn it) and as many users report making it work, it did reducing the working life until it died. Yes I tried that too, and no, no direct power and no LM317 working on my case.

 

[Cyparagon]

The word you're looking for is driver. The LM317 regulates current or voltage, it is not a power source.

A "common adapter sold at radio shack" Outputs constant voltage. You want constant current instead. It may or may not have some form of overload protection, where it simply shuts down if the load draws over 300mA (or whatever the current rating is).

A "USB port" also provides constant voltage, not constant current. USB has overload protection as well, but that is not the same as constant current.

The LM317 based driver is a very simple circuit. If you tell us exactly how you constructed yours, we can tell you what you did wrong.

 

[hroldan]

The word you're looking for is driver. The LM317 regulates current or voltage, it is not a power source.

A "common adapter sold at radio shack" Outputs constant voltage. You want constant current instead. It may or may not have some form of overload protection, where it simply shuts down if the load draws over 300mA (or whatever the current rating is).

A "USB port" also provides constant voltage, not constant current. USB has overload protection as well, but that is not the same as constant current.

The LM317 based driver is a very simple circuit. If you tell us exactly how you constructed yours, we can tell you what you did wrong.

Hi Cyparagon, yes, the right word is "Driver", for the burning laser. After reading several tutorials decided to try the following two, didn't work for me, must have done something wrong but can't tell by now what it was. In both cases diff lasers shined but it got hot regardless of the heat sink. Measured the voltage output and found out it was the same as the one feed into the circuit. Current? I trusted the components (that's my mistake I guess, instead of measuring) but had no idea then.

Laser diode circuit
How to Build a Laser Diode Circuit

Homemade laser with LM317
Homemade Laser Driver with LM317 - Langeder.org Blog

Then tried this one:
DIY simple power driver for burning laser from old DVD
https://www.youtube.com/watch?v=eueQ1TwL7gg

Important lesson learned: will test the circuit on normal LED diodes and measure both the voltage and the current to avoid working directly on the laser. Any alternatives and advice will be appreciated, it seemed so simple but I'm learning this is not that easy. Thanks!

 

[hakzaw1]

are you following correct ESD precautions?
do you know that the current of your driver must be set using a dummy test load NOT the laser diode(sure death)--- working preset drivers can be purchased VERY cheaply--I think you underestimated the mount of study this takes..

are you sure about the pin-out?
$ NEVER power any laser diode with a battery and no driver.

see what is available at AixiZ Laser.

Please add your country/location to your profile!!

 

[hroldan]

are you following correct ESD precautions?
do you know that the current of your driver must be set using a dummy test load NOT the laser diode(sure death)--- working preset drivers can be purchased VERY cheaply--I think you underestimated the mount of study this takes..

are you sure about the pin-out?
$ NEVER power any laser diode with a battery and no driver.

see what is available at AixiZ Laser.

Please add your country/location to your profile!!

nope, and nope, that's a big on why I failed, but sure learned, yes I underestimated the precision of this case. Yes I'm sure about the pint out but I will assume "no" as in starting from scratch now.

I live in Guatemala/Central América, just browsed the AxiZ site, will check it out with more time at night to see what I can buy, probably a friend over there coming in Jan can bring it home (if the shipping is fast at least one week from today).

Any recommendations will be appreciated. I'm building a cnc and want to add laser engraving for wood and plastic mostly.

 

[hakzaw1]

TY and Welcome-not too many members from there afaik.
AixiZ ships world wide.

here is a lucky +7 rep bump for you-

hak

 

[hroldan]

TY and Welcome-not too many members from there afaik.
AixiZ ships world wide.

here is a lucky +7 rep bump for you-

hak

Thanks, I will continue trying, I still have some electronics (always buy at least double in case of burning something), so, some more test drive before buying it as a product (I like trying to build things).

 

[hroldan]

Update:

Tried again the same schematics and electronics. This time religiously taking care of recently lessons. Didn't use the laser, instead placed an LED for testing, tried several times and finally got the first stage: constant current. Then went to try 5 different DVD burner lasers. The dvds I got had 1 laser, and the other ones two each one (5 in total).

Laser #1 went on like the led, but it's weak :|
Laser #2 no visible light :/
Laser #3 very... very weak light :/
Laser #4 no visible light :|

Laser #5, nice light using 3 AAA batteries
Switched to an old adapter rating 6V - 300mA, now I have strong laser light.
Tried an adjustable lens, it focus the beam but it doesn't burn. Oh but it doesn't get's hot! and that's good because it means I will not burn the little piece as the current is on the safe range, right?

I've seen a lot of tutorials and vids (working) using 6V from AA batteries and also 9V, I guess I will try that instead of this wall adapter (6V-300mA). Any comments will be welcome and well appreciated.

 

[RedCowboy]

Are you using 660nm diodes or ir, they are static sensitive, you should avoid touching the pins.
If you are using 660nm red diodes the internal resistance of a pair of double A alkaline batteries will often work, just connect 2 AA batteries in series through a switch to your diode, polarity matters and your diode should be heat sinked.

 

[hroldan]

Are you using 660nm diodes or ir, they are static sensitive, you should avoid touching the pins.
If you are using 660nm red diodes the internal resistance of a pair of double A alkaline batteries will often work, just connect 2 AA batteries in series through a switch to your diode, polarity matters and your diode should be heat sinked.

I honestly don't know, the laser comes from one of the old DVD burners. To my surprise it burns!, tried several things and even *carefully* sensing the heat but no luck, then accidentally moved the back tape in front and noticed smoke. This laser burns dark stuff, tried paper but no luck.

The laser has 3 pins, two of them came soldered already, this means I have two places to connect the current, so this, it works and it burns. Would it work better if I separate the pins? I've seen tutorials where the guys chop the "unused" pin.

 

[hroldan]

Update, dvd laser burning

are you following correct ESD precautions?

Oh so valuable. I want to share my results so others can find detailed information on this thread. Very important: discharging. Take care on the electrostatic discharges and put tape on the cables to avoid accidental touching, or get yourself some help with a protoboard. Discharge the CAPACITOR and use a LED. This is very important, place the LED instead of the laser diode to test your circuit and measure the current and voltage.

Once the circuit is ready: discharge the capacitor and cut the current/voltage before connecting any laser diode. If you don't do this (like I did... things go wrong), the capacitor will shot a high voltage/current to the diode damaging it or killing it. So, connect everything to your tested circuit and then apply current. And yes, use protecting glasses and if possible place the laser diode with it's sink on a fixed position to avoid accidental movements directing the laser to your eyes.

I'm using the LM317 driver with a heat sink, the components are the usual configuration, this image is from this forum on another thread

I'm using a red laptop DVD laser
6.8 ohm resistor (5 watts) instead of the 10ohm
the diode and capacitor as the circuit advice

Had trouble with the 100 ohm so I removed it, it works pretty well. Any comments on this will be appreciated. I'm feeding 6 and 7.2 volts with no problem.

For one of the laser diodes I'm using a lens from one of the units, for the other I'm using an adjustable lens from a laser pointer (clean it well). Not all the lenses from dvds work, some focus the light just too close, some too far, try until you get the desired results.

Mine is burning dark colored foam and black tape, it can also draw very thin lines on wood but it takes time. I'm already testing it with my DIY CNC.

I've seen pretty powerful laser videos on the web burning wood better than mine, any advice on this to improve the results will be welcome, I'm not confident on feeding more than 7.2 volts for now until I get more info, took me a lot of time extracting and setting things up to blow it without enough research.