This tutorial will explain every little thing you need to know about how to build a burning laser, it's an interesting project, which is still quite easy to make.
The picture above shows how mine looks but you can make the design of yours look totally different if you want to.

It's going to become a burning laser with controllable current. (current-regulated with an LM317T).
You can choose between a 9V battery and an external power input (see first picture on the left side).

Other regulators then an LM317T are also possible to use here. If you have any questions about them, ask it here!

It might be fun to have a burning laser, but not when it burns that one thing you don't want it to burn.
Use safety glasses! This is really not a simple toy.

High power lasers might also not be allowed in your country, keep that in mind.

I am not responsible for any accidents with this device, however all dangers are well noted in this instructable.

A video of the laser in action:

A video of the laser in action with a spirograph:

Step 1: Requirements

The set-up is really simple, there are just few components:
(* means Required)

- Hot glue or other glue.
* A soldering iron /w soldering wire.
* A laser diode.
* A 100ohm potentiometer. (250mW)
* A 3.3ohm resistor (or 3x 10ohm resistor in parallel). (3x 250mW or 1x 0.5W).
- A regular diode 1N4001-1N4007 (everything between is also good).
  (or any other diode that can hold a reverse voltage of at least 40V)
- An On-Off switch/push-button/... as a main switch for the circuit.
- An On-On switch for switching between battery or external input.
* A 9V battery clip. (click here if you don't have one)
- A 9V battery. (not required if you use the external power input)
* An LM317T regulator (really cheap).
- An enclosure/box to put the whole project in -> I used an 8*5*3cm = 3.15*1.97*1.18inches black project box.
* A lens for adjusting the focal point of the laser beam.
- A connector for the external power input (if you want to use that).
* PDF reader for the datasheets.
* Your healthy brain and attention for safety measurements.

MichaelP598 days ago

I just get artictle about <a href="http://911electronic.com/tunnel-diode-characteristic-symbol-definition/">tunnel diode</a>, if you need to get more information about this electronic device check this

Can i use a 1n4148 diode instead of the 1n4007?
Electorials (author)  anubhavtalukdar0072 years ago
You can use it, but because the maximum current is only 200mA, if you will be using strong laser diodes, I suggest you put two 1n4148's in parallel, so that they can handle 400mA.

NOTE on DIODE in PARALLEL: Resistance decreases in diodes as their temperature increases which is why diodes, LED's, Laser Diodes, etc, need to be CURRENT LIMITED... If two diodes are wired in parallel, whichever one is hottest will pull the most current, get hot and burn out... then, due to burned diode, all load would be put on the next diode in parallel...

(The lm317 is excellent for limiting current to any LED / Transistors / Laser Diodes)

Hope this helps!


No. The 4148 is a low power signal diode and the 400x series are made for at least 1 amp of current.

tanjamaya29 days ago

Hi there, I'm trying to build laser driver from DVD laser diode for engraving machine... here is my fritzing file, can you tell me where I'm going wrong


mannudhadse1 month ago
AbdulazeezU1 month ago
Be Straight Pls Am New R1 Or D1 And Voltage
R3dStamps2 months ago
Do a NTE958 also work?
what voltage requires a 2 w laser?

would be cool if you'd give more details

what voltage ? amps ? polarity ?

can i make a burning laser from a key chain laser pointer by fed it more current if not why and laser watt depend upon what ? why a specific laser diode is use

That's like asking why can't you just feed more current to a desk lamp light bulb to turn it into a floodlight or spotlight. They aren't built to accept that much current, so they will blow out. Lasers are developed to emit light with a certain intensity at a certain current, and this intensity transfers energy. That process is basically the power of the laser, and power is measured in watts. Even if you get the most powerful laser in the world, you can't simply feed it more current to make it more powerful, as you will still blow it out after you exceed the maximum current the diode can handle. If you want a fun little laser toy it will have a cheap, weak diode of 5 milliwatts, or .005 watts. If you want a laser that is capable of burning something, you need at least 100mW, but even then it will be slow. The more watts your laser diode is, the more powerful it will be and the quicker you can burn, melt, or pop things!

3XTR3M1ST4 months ago

Saw quite a couple of these instructional videos and everyone's saying to extract the diode and build a driver for it on another heatsink/casing.

But I just wonder why not just leave the diode as it is in the laser carriage assembly and simply power it up with whatever ribbon cables it is attached to?

Saves all the trouble don't it?

A.C.E. 3XTR3M1ST2 months ago

Since nobody else answered you, I'll try and answer. I believe that the dvd drive only uses short, low powered pulses for writing to a disc, and also the lens build into the carriage focuses at 3mm or so from the lens, which would not make ANY kind of beam. It is also non adjustable, so you're stuck with tat short focal length. It probably can't take higher current to do real burning jobs with the minimal heatsinking that the carriage would have, as well.

Most people use an aixiz laser housing which is cheap and solves 2 of those problems above: heat and focusing lens. All that's left after getting the diode into the housing is building a driver so you can supply a clean current to the diode, and you're good! The housing is tiny too so you can fit it into things like a flashlight or project box easily.

A.C.E.2 months ago

I made my own driver with an lm317 and a potentiometer that had adjustable voltage. I tested it on an led and a 5mW laser diode and found it to be working, but then when I hooked up my dvd drive diode it got dim after about 20 seconds of use with the driver set to 2.8 volts. Is limiting voltage the wrong thing to do? Your driver is only slightly different than mine, but I'm wondering how if I limit only the current, the 9 volts from my battery won't blow the diode out instantly? Also, I'm correct in assuming that you can't regulate both the voltage and the current at the same time, right?

chintans3 months ago

please update

dharun3 months ago

where do you get the lens

howtodosteps6 months ago

Why is it that when i apply 9V battery DC directly on the DVD laser diode it is not light up? Am i doing it over voltage and fried the diode?

DGW howtodosteps6 months ago

People, please realize that all LEDs and Laser Diodes must be current limited or they will burn out instantly! At a minimum they should have a correct resistor in series with them to limit the current to the max allowable shown by the spec sheet. Even better is to use a current regulator as shown in this Instructable.

you actual broke it, he uses a current limitation, that means that thevoltage steps down until a specified current will flow.

ir_One1 year ago

Hi , i have cd burner,..are its can be used for laser burn...?

DGW ir_One6 months ago


How can I convert this to work on a battery bank with 4 AA batteries? I'm making a laser gun and there is already a space in the casing for this bank. I would rather use that than a 9V. Or, better yet, convert it so that it can alternate use between the 9V and the battery bank.

DGW metalshiflet6 months ago

It will work on 4AA batteries just as well as a 9V if the diode drop is less than 4V as it often is. (Depends on what laser diode you end up with. Hard to tell when you are extracting them from a DVD burner.)

I looked in Radioshack and could not find a 3.3ohm resistor. What other names are there for it?

DGW metalshiflet6 months ago

Go to Jameco.com and they will have it.

gschafer8 months ago
I've made the circuit and tested it, and it appears either my LM317 is broken or I don't have it wired properly. Can anyone show my how they have their LM317 wired?

i should be able to connect the diode straight to my lab supply, right? i can tune the supply to the hundredth of a volt and the thousandth of an amp.

Pbyrd1 year ago
Would a 7805 regulator work here?
a lm7805 is a voltage regulator not a current regulator.
Electorials (author)  Pbyrd1 year ago
Not really. The voltage over the potentiometer and resistor (5v in this case) would be too high. When you increase the output current, the power dissipation in the potentiometer will just fry it.

In the instructions it said you could use one.

Where can I find an lm317

glitvjaks1 year ago

Great instructable! Easy to follow but not dumbed down. I used your circuit today to make a laser spirograph (although I am using a laser module meant to be powered by batteries instead of a bare laser diode) and it worked just fine!

djmelvinv1 year ago
hi. is a dvd diode exact the wavelenght of 650nm or is there an range? I just want to find the glasses maching de dvd burn diode wavelength and want to be very sure there is no IR.
kgaurkhede1 year ago

plz help me to make a circuit for powerful laser which can burn plastic sheets of almost the thickness of 3-4 paper sheets
n of what power the laser diode should be???

thnx in advance

kgaurkhede1 year ago

plz help me to make a circuit for powerful laser which can burn plastic sheets of almost the thickness of 3-4 paper sheets
n of what power the laser diode should be???

thnx in advance

mkhurram1 year ago
Hey electorials! Loved the instructable.....can this thing cut acrylic ,plastic boxes etc. as well??
im using a diode from a dvd burn... but it not burn!!! why? can you help me? im usin a circuit with LM317
brunodiaz202 years ago
cool gonna make one
dudefrom982 years ago
I got 6.88 volts as the output to go to the laser. Is this fine or should I put a regulator on it?
SpecieS~3 years ago
Hi, I'm wondering about the limiting potentiometer. Do you connect it exactly like the one for regulating the intensity? And do you still use 100ohm for regulating or do you change the value?

greetings, SpecieS
Electorials (author)  SpecieS~3 years ago
I still use the same value, 100ohm (but I think 50ohm would be a little better, not sure).
It is indeed connected exactly the same, and placed in series.
Thanks for your fast answer. I found some 50ohm 1/2watt precision trimmer, which would be perfect for the limiting job :D
A 300ohm resistor in parallel to the regulating potentiometer would reduce its maximum resistance to 75ohm. Seems to be a good compromise :)

greetings, SpecieS
Electorials (author)  SpecieS~3 years ago
You say 'reduce' it's maximum resistance, but you say it goes from 50 to 75 then?

Indeed, a 50ohm trimmer would be nice.
When adding a resistor in parallel over it, you'll Decrease it's resistance, not increase to 75.
And also, when you added a resistor in parallel, the track resistance won't e linear anymore.

You don't need to add a parallel resistor, the 50ohm trimmer is perfect.
Oh, you misunderstood what I said. I don't want to decrease the trimmers resistance but the regulating potentiometers resistance from 100 to 75ohm.
Electorials (author)  SpecieS~3 years ago
Ahh yes, I see now.
but I don't think you'll get "more precision" out of it by doing that because it will make the slider non linear.

At the lowest resistance values, it will change faster now.
Indeed, it makes it non linear, but I've inspected the function in kmplot and the graph is almost linear: http://img836.imageshack.us/img836/6051/resistancegraph.png

btw, I've made some new schematics including the second potentiometer using Eagle: http://img845.imageshack.us/img845/3899/schematicslaser.jpg
You may attach it to the instructable if you want.
Electorials (author)  SpecieS~3 years ago
It al looks really good.
The schematic is also good but I think I'll just keep the one that I already have.
My parts arrived today and I tried it out on a breadboard. The trimmer became hot so I removed it, but then turned the other poti a bit too far. :S
Fortunately I have another dvd-burner laying around...

ps: Happy new year :)
Electorials (author)  SpecieS~3 years ago
The trimmer's power rating must have been to low.
I hope you got some nice results before the diode got fried? :)

Oh, and it's normal that you fried your first diode. You'll do that 10 more times haha! :)

Happy newyear!
Well, according to the datasheet the trimmer's power rating is 0.5 watts at 70°C decreasing linearly to zero at 125°C. But obviously my diode exceeded this limit ( I suppose it was about 0.7 watts or more). I think next time I'll use the big poti to adjust to the right resistance, measure it and use some resistors in parallel to set the minimal resistance.

And I hope I don't need ten tries to build a working laser :D
Electorials (author)  SpecieS~3 years ago
Tell me,
How is your laser now?
did it work out? :D

Hi there,
it works, but I don't have a collimator yet. I've already tried focusing the beam with a single lens, but it didn't burn anything. Maybe the diode is too weak. It's a bit smaller than usual, because it's from a laptop dvd-burner.
Electorials (author)  SpecieS~3 years ago
Wow! it's looking really good :D
It's nice to see that other people are also making this ;)
Good to see a picture of it!

And yes, the diode is probably just too weak.
However, DVD burner diodes should do the trick
Maybe it can handle more current than you are giving it now?
Hey, I finally made some pretty simple optics from a ball pen and one of those lenses I kept while taking apart the drives. I also made a "quick 'n dirty" double-slit out of paper. The second picture shows it's interference pattern :D
Electorials (author)  SpecieS~2 years ago
That looks awesome :D
Today I tried out some other materials for double-slits. Aluminum foil worked quite well, so I finally decided to make an 'ible of it :)
How To Make a Simple Double Slit
digas4 years ago
Every time i disassemble a dvd burner i get the diode , but the diode does not work! Any suggestions?
nbeched digas2 years ago
Just to add:
It's either the heat from the soldering iron or static discharge that very quickly destroys the diode. It doesn't have to be a massive/powerful discharge that you feel...

The safest thing to do is when you desolder the diode, solder or wrap a piece of wire to both pins so that they are always at the same potential and remove this wire right when you are ready to solder something else to it.

Also, don't forget that it is a diode, so it is polarised, meaning, if it does not work, try reversing the +/- to it.
Also, if you don't use the LM317 method described here, have some series resistor as supplying too much voltage will kill it just as quickly as a static discharge...

Have a good one.
Electorials (author)  digas4 years ago
Did you solder anything to the diodes before you tested them?
maybe the heat of your soldering iron kills the diodes :/
nop, no solder!
Electorials (author)  digas4 years ago
and other diodes do work? or did you only try dvd burner diodes yet?
only tried dvd burners!
Electorials (author)  digas4 years ago
Then your diodes are probably not broken. I hope you didn't throw them away!

Could you tell me something about what driver, what pins on the diode (and polarity), power supply, resistors (if LM317), ... you are using?

(if you want to, you could also send me some pictures of the setup. it'll be easier for me to understand then).
I didn't threw them way, but I don't know where they are! :(
They all had 3 pins!
Electorials (author)  digas3 years ago
:( not good
oppie digas4 years ago
The laser diodes I've worked with are three terminal devices. One pin is the common. One pin is the laser diode and the other pin is an internal photodiode that monitors the laser output. Idea is to run the laser in closed loop at a stable optical output.

A laser running at very low current is no more than a LED. As you increase the current, light gets brighter and starts to transition to coherent radiation (LASing). The difference between the lasing threshold and overload where you destroy the diode out is rather small, hence the desire to use a closed loop optical feedback. This also compensates drive current for die temperature variations.
Typical diode datasheet http://media.digikey.com/pdf/Data%20Sheets/Sharp%20PDFs/GH06510B2A,B.pdf
Some good applicatoin information http://www.repairfaq.org/sam/laserdps.htm
Electorials (author)  oppie4 years ago
What you say is true, but I don't really see how it helps digas?

And that last link is indeed very useful ;)
Sorry, I got distracted and had meant to add that he might have connected to the monitoring diode instead of the laser diode. Would be plausible reason why there was no light output but current being drawn.

Laser diodes are also rather sensitive to heat, mechanical shock and static discharge.
Electorials (author)  oppie4 years ago
Ahh ok ;)
maildude2 years ago
does anything change if u use a blu ray diode?
do u need a other regulator or other different parts?
Electorials (author)  maildude2 years ago
No, it'll be the same components :)
Selmerman3 years ago
hi, quick question, I have a small 28 turn 100 ohm potentiometer. how would I wire this potentiometer. This potentiomer has the number 3296 and is made by King.
agedesign3 years ago
i'm just learning in electronics but this lm317 sounds like a simple voltage regulator and if so at what voltage does it regulate at
Electorials (author)  agedesign3 years ago
It's not just a simple voltage regulator.
It can be used as a voltage regulator and it can also be used as a current regulator (which is what we use it for here).
The current can be set by changing the resistance between the output and adjust pin.

There are also other voltage regulators around which indeed just have a fixed voltage. For example: an L7808 will have a fixed voltage of 8V.
What a kind of diod and what kind of lens I should use
E mail for arsalanmzz@gmail.com
thonypogi3 years ago
awesome ! :D

can i ask question ? in your 1st video, you labeled a trimmer potentiometer.
but it is not in your list of materials and circuit diagram.
only large 100ohms 250mw potentiometer.
what is the purpose of that pot and where i'll connect it on circuit ?

and how can i extract laser diode on "tiny thing" that extremely glued or epoxy ?
can i grind it using small file ??

thanks ! :)
Electorials (author)  thonypogi3 years ago
Hi there!

The trimmer potentiometer is a 50ohm cermet 20-turn trimmer
(0ohm to 50 ohms in 20 turns)
which allows me to regulate the current trough the diode Very precisely!
It's connected in series with the original potentiometer, and works just the same way ;)

For extracting the laser diode if it's glued into metal parts, It seems to work best for me to cut open the metal piece with cutting pliers (so that it kind of breaks open; enlarges the hole where the diode fits into, while you cut in at the sides).

If that doesn't work, try heating up the metal with a soldering iron or something else, that'll loosen up the diode :) but don't heat it too much, and also not for too long because that might kill the diode!

I can't really explain very well about the cutting with pliers in the metal, but if you could show me a picture of that metal piece, I can work out the best way of getting it out of there ;)

Great idea! Really looking forward to trying this. I pulled the laser diode from a working CD burning drive last night, and it went beautifully. Thank you for all the pictures and detailed steps.

My idea is to use this to mark parts for my current large project. Each part needs to have a unique number, and I think it could be possible to control this laser with an arduino and some servos to create a (somewhat precise) laser etching tool. We'll see.

I have a couple questions about the infrared laser diode harvested from CD burners. First, if connected as described, could this be used to etch aluminum or (unhardened) steel (assuming that the servo speed was set very slow)? Second, I have limited experience with lasers, and none with infrared. I am a photographer, however, and highly value my eyes. What safety equipment should be used for protecting myself from infrared laser radiation? I do have night vision goggles, but would this be an effective way of focusing the beam? Would the NVG's be damaged in the process (or could they)?

Thanks for such a thorough instructable. Again, loved the photos!


Electorials (author)  huck alexander3 years ago

Thanks a lot for the reply and for following :D

Regular CD burner diodes are not able to etch aluminium.
At least not all the ones I have tested. I think you're going to have to buy a different diode for that.
They are very capable though of etching dark plastics.

And great idea of combining this with an arduino!

About the safety glasses; I don't know a lot about them, but what I do know is that it isn't "one type of safety glasses for all types of lasers"
That definately not.
You'll have to know what frequency (or wavelength) the laser emits, and the glasses you buy have to work for that frequency!

There are some types of glasses that block for example red and blue lasers, but I don't think there is any type that blocks them all.

And I won't try the nightvision goggles. The laser would just burn holes trough the films I guess :/

Thanks for the reply!

Thanks for the suggestions. After a bit of research, it's clear that protective equipment for laser emitted radiation is based on wavelength. Will have to find the right equipment for my diode.

When you created this project, did you use safety equipment? If so, what did you use to protect yourself from a high powered red laser? Was anything special require to protect skin while focusing the beam?
Electorials (author)  huck alexander3 years ago
I use safety glasses that came with another laser I once bought.
I don't know a lot about them. All I know is that they work for red lasers.

You don't need anything to protect your skin with these lasers. I never had a diode yet that would instantly burn your skin.
Although, if I focus one of my best laser diodes on my skin, it does start burning after a second. But still, a second is really long :)
lis.tesla3 years ago
sorry im kind of a n00b
but what do you mean
(3x 10ohm resistor in parallel)
Here is a good link!
Mavamaarten3 years ago
I'm having trouble with my diode.
Whatever I try, it does not emit any light (not IR either, tried with my camera).


What am I doing wrong?
Electorials (author)  Mavamaarten3 years ago
Wow! I've never seen a diode with that many pins o.O

However, because you uploaded a nice picture, I can still make something up from it.

There is One pin which is not insulated; directly connected to the metal piece.
That pin is always the negative pin.

Since it's a diode, putting voltage with the wrong polarity on it, shouldn't have killed the diode. So it's most likely still functioning.

In my picture, the pin on the right (middle pin from the 3) is marked as negative pin,
and with all diodes I have, that pin is also directly connected to the casing.

Now you know what the negative pin is, but still not the positive :/
I suggest you try the first pin anticlockwise from the negative pin. If that doesn't work, try the second pin.

I doubt it would be any of the other pins, but it's possible :) so keep trying.

What kind of diode is this? is it a multi colour diode? since it has so many pins?
if so, multiple pins will probably work for different colors.

Keep trying with your camera as well as you were doing ;)

Tell me if you have any trouble!
I hope I helped you out a little :)

Thanks for the reply! I didn't notice the non-insulated pin, thanks!
I got it out of a CD-Burner. Oddly enough, there was an odd-looking component inside too, which turned out to be a working laser. It's not a burning one but it does work. That laser and this one were connected using an odd system of mirrors and stuff, I have no idea what kind of laser this is.

All tutorials about lasers I have seen before only have 3 pins. Oddly enough mine has a lot more!

I'll try and fiddle arround with it some more. Thanks for the tips!
Electorials (author)  Mavamaarten3 years ago
okay ;) nice to hear that!

and the mirror stuff is there in every cd burner :)
it's used to focus the beam of two lasers (one for reading and one for burning) into the same point, where it'll read and burn into the disc.
francisdsa3 years ago
Hey there. just curious about the lens. where did you get your lens from? can i use a lens from another cheap laser keychain thingy or stuff? or can i use the one that came out of the dvd bruner? any ideas where i can get these lens from? or make them? or buy them?

please reply
Electorials (author)  francisdsa3 years ago
I also got mine from those cheap lasey keychain thingies ;)
There are lenses in the dvd burners and readers aswell but they are always bad lenses :/
I haven't found them anywhere else yet but from those keychain lasers.
prodriverex3 years ago
Hi Electorial,

Thanks for sharing. I have all thie parts secured except for the laser diode,very tempted to buy off RS Component or Farnell but they are costly. At least there is a 405nm option about 80bucks. But their rating stated values like max optical output 100mW, typical op voltage 4.6V, typical op current 0.12A.
How does 1500mW fit into these rating? Can a 100mW diode take 1500mW base on your logic? Most likely i am misunderstanding your power definition. Or, the diode from a DVD burner is higher than what i found here?
Electorials (author)  prodriverex3 years ago
Oh no
That 1500mW is the maximum power the driver can deliver.

There are indeed some diodes which are that powerful, but if it's a 100mW diode, it's maximum power is 100mW. If you go above that value, the diode will get fried.
hehe.. ok I got that..
Also, can we use TTL laser diode too? Or only Linear diode for this circuit?

Electorials (author)  prodriverex3 years ago
You can make a TTL circuit that makes this driver go on and off but I think it'll be better for you to use a current regulator which has an 'enable' pin.

Sorry for the late reply :/
undress153 years ago
I'm new to DIY technical projects in general, so I pretty much do not know where to get any of these parts. Any suggestions?
Electorials (author)  undress153 years ago
I have no idea where to find these in other countries :/
I bought them at my local electrical shop.
Sick! This is my next mad scientist project! Excellent instructable!
Electorials (author)  solomonhorses3 years ago
Thank you ;)
robot13983 years ago
will i get a laser in floppy drive
Electorials (author)  robot13983 years ago
No, floppy drives don't work with lasers.
Dreistein3 years ago
i love these instructions for the reasons that you show how to make everything and you don't need any laser module
Electorials (author)  Dreistein3 years ago
Thanks :)
colorex3 years ago
OK, I'm new to electronics... My store has LM317L, LM317LZ, LM317T, LM317K
Which is best?
Electorials (author)  colorex3 years ago
The LM317T is good ;)
Electorials (author)  colorex3 years ago
Could you post some pictures here when it's finished? (or when not finished yet is also good)

I'd like to see it ^^
When I do this, I will share it! (that may take some time)
Electorials (author)  colorex3 years ago
Ok :D

Yes you can use more than one potentiometer but I wouldn't suggest that. If you take 2 50ohm's instead of one 100ohm, you'll be able to controll it more precisely but it's not really logical to control one action with two different potentiometers.

You can use 2 pot's if you use the first one to set the "maximum current" and tjen don't touch it anymore. Then you can use the second pot without needing to worry about killing your diode.

In this case, I suggest to use a 50om trim potentiometer for the first pot because these are a lot more precice!

If you'll use just one pot, I suggest to use one with multiple turns, like a trim pot.
(3 to 10 turns) that would also just be a 100ohm pot.

If you have any other questions, don't hesitate to ask them ;)
I can't wait to see some pictires :D
OK: so i got the LM317T, I got a diode 1n4007, I got 3 x 10ohm resistor, i got the push button, and i got the 100ohm pot. However, it's not a multiple-turn pot, and I do not know the wattage. It looks like this: [Image below]  Is it the right one or should I get something different? They only have higher ohms, 1k and up.
Electorials (author)  colorex3 years ago
I'm sorry, but that is really bad.
That's a 0.1W trimmer potentiometer.

It's not a multiple turn POT, however, mechanically you can keep turning it.
It starts from 0ohm again after you complete one circle.

You can't use that one because it's power rating is too low. It'll burn up (laterally)

I Suggest you use one Trimmer potentiometer (cermet) to set the maximum current value, and another Regular potentiometer for also adjusting the current from max to minimum.

This has the advantage that you can't kill your diode by rotating the second, regular potentiometer.
yes that was what i was thinking. but what other options do i have? like, what pot could I use? what about the 1000ohm? can you explain what's the difference?
Electorials (author)  colorex3 years ago
I hope you didn't buy that trimmer potentiometer.

Because you don't want to use just a 100ohm pot but a 1000ohm pot, I'm assuming you have those laying around.

practically, a 1000pot will be terrible to use, because from 0 to 350° you'll have almost no light being emitted by the diode.
at 355° you'll get the maximum intensity, and at 357° your diode will be dead.

I don't think you can rotate a potentiometer at 0.1° precision.

(just fictive values that I just invented, but it will really be something like that).
Really impossible to regulate the current with a 1000ohm pot.

If you have a 50ohm pot, that might be possible too. I never found these, even not in stores.
(but with a 50ohm pot, you won't be able to set the light intensity to low values, only from half-bright to full brightness)

100ohm is really the best you can do.
OK, now I understand. Is there any way to increase the wattage capacity, or reduce the amount of watts needed for the pot?
Electorials (author)  colorex3 years ago
you can't reduce the required wattage because it's determined by the current that needs to go trough your diode.
With lower wattage, your diode won't get bright.

You can't increase the wattage of the POT.
You'll have to use another potentiometer, there is no other way around.

what potentiometers do you have laying around?
Is this a trimpot? It does not state numbers nor capacity. It's mounted on the PCB of an old radio/casette player
Electorials (author)  colorex3 years ago
The one above? yes it's a trim pot.
I got the number 0.1W by comparing it to others online, of the same dimenisions.

you really can't use that thing.
oops, forgot the image...
Electorials (author)  colorex3 years ago
thought so.. :)

Uhm ... let's see..
I can't find any information about what wattage that old thing is. I've seen them a lot before too, on old circuit boards, but if I was you I also wouldn't use it.
I think it'll stop working after adjusting the pot 50 times.
Hey, what about guitar pots? I think they have lots of those... Are they too high ohms?
Electorials (author)  colorex3 years ago
Those are 50.000 to 250.000 ohms. Out of the question.
****. Well, I'll keep looking. Can you give me the highest and lowest margins acceptable?
Electorials (author)  colorex3 years ago
Lowest: 50Ohm
Highest: 200Ohm (Really not higher, I would more like to say 150ohm as maximum, but 200ohm is really the absolute maximum)

Wattage: 120mW (don't go below it) higher is not a problem.
OK, thanks. I'll keep looking.
Electorials (author)  colorex3 years ago
Good luck ;)
Would this work? What effect would it have?


Would they be connected in parallel or series?
Electorials (author)  colorex3 years ago
They might work, if the resistance values are good.
They don't need to be connected in parallel or series. Just use only two pins.
So if i put 4 100ohm pots together with 0.1 W each it would make one 100ohm pot at 0.4W? Is this correct?
Electorials (author)  colorex3 years ago
No, it won't be 100ohm anymore then.
OK, I got that 5 500Ohm resistors give out 100 ohm when put in parallel. Is this right?
Sorry for being so annoying...
Electorials (author)  colorex3 years ago
Yes, that's correct.
According to my cheap clculations from an old physics book, the resistance would be 33 Ohms. Let me figure out the rest.
Electorials (author)  colorex3 years ago
Oh, I mean 25.
BTW can't you put two potentiometers in series for fine tuning?
florman3 years ago
Can you pop a balloon with the laser?
Electorials (author)  florman3 years ago
Yes, I can, but it depends on what diode you have in it.
I currently have a DVD burner diode, and it easily pops a balloon.
florman3 years ago
Is the lense a magnifier? or is it just piece of glass?
Electorials (author)  florman3 years ago
It's a magnifier. :)
Electorials (author)  Electorials3 years ago
and it's also the only part that I can't recover from anywhere.
I try to recover as many objects as possible from other broken things, but I can't find a good lens for this anywhere else :/
hjartland3 years ago
Novice question. What about eye protection? Aren't these lasers housed in a drive for a reason?

Thank you,

And GREAT instructable!
Electorials (author)  hjartland3 years ago
they are dangerous yes, but I can't tell much about the laser glasses because I don't know a lot about them :/
sueman23 years ago
so it is voltage that really matters for lasers right? too much easily fried, but amperage is kinda irrelevant.

I want to do alot of experimenting with lasers in the future, so would like to create a constant power supply that outputs 0-8 volts. that should be able to power what ever i throw in right? also kill some too. So what i would do is start at zero and move up till it it concentrated, right? or would this not work? anyway, main point, what items would i need? a regulator, power supply, a pot, other stuff. i kinda know what to do, but not at all. so could you help me out? anyone for that matter. assuming you have knowledge to share.
tim1273 years ago
what would happen if i just used the LM317? i dont know a lot about this stuff
Electorials (author)  tim1273 years ago
Take a look at this datasheet, at page 12:

The T means it will be a TO-220 package (that means the shape of the voltage regulator)
There is no 'LM317' without any other character added to it.

LM317T: TO-220
LM317S: surface-mount
LM317K: metal can
.. and so on

I still suggest to use the T or K version because when using another version, the maximum allowed current also differs! (see page 3 in the datasheet "current limit").
redink3 years ago
What is the highest watt of laser diode that can be used with this circuit.
Electorials (author)  redink3 years ago
1500mW theoretically (electrical power, not optical)
Your heatsink may be larger than needed for heat sinking, but it's not too big for the project and looks really cool.
Electorials (author)  dustinandrews3 years ago
haha yes, I know it's to large but it looked cool ;)
techxpert3 years ago
with the 100Ohm pot can you replace it for a resistor that gives the laser it's full out put all the time
Electorials (author)  techxpert3 years ago
Yep, if you want maximum output always, just remove the POT (no other resistor should come in place).
techxpert4 years ago
this works on 4v right so can you put a 5v battery instead of a 9v because i want to put this in a torch case
Electorials (author)  techxpert4 years ago
I don't think a 5V battery will be enough.
are you sure because i want to fit this in to a aerospace grade aluminium torch case see what i'm getting at
If you need it to fit in a torch case and run from a single lithium battery, you are better off buying a driver off ebay.
If you are good at soldering really small smd parts, there are switching laser (or LED) driver ICs available that have very little voltage drop, or that will step up the voltage.
The LM317 drops at least 3 volts when used as a current limiter, so it will need 2 or 3 lithium batteries to run it, depending on the laser diode voltage.
Electorials (author)  techxpert4 years ago
it Might work with a weak diode, but a DVD burner diode will not operate on a 5v battery. (keep in mind that the LM317T also requires 3V operation voltage.
pepehdez4 years ago

Based on the info rkey provided, I did a search on ebay and found a few laser safety glasses starting from $15.99, I searched for "laser glasses 650nm" the lens are blue for some reason.
Electorials (author)  pepehdez4 years ago
Yes indeed, for red lasers you need blue glasses

And they aren't really cheap but it's worth it :)
Can't you make your own glasses as long as you get the right filter material?
Electorials (author)  reddevved4 years ago
I'd also like to know how to do that
They are indeed. Even if you have safety glasses, you should still practice safe operating procedures. Know where the laser beam is going and avoid any reflective surfaces. The safety glasses are a last resort measure and you should never depend solely on them to protect your eyes. You only get 1 pair :)
if i have to buy a high power laser in a store ...what should i ask for ...i.e. in what specifications???
plz help ....
Electorials (author)  rkrishnakumar4 years ago
uhm I don't know if you can buy laser diodes in a store.

and I don't think stores sell high power lasers since that's not really allowed.
is it possible to use the laser diodes inside DVD burners?
Electorials (author)  codestroy74 years ago
Yes, they are perfect for this project!
merkindesr4 years ago
I have hooked up the parts using this exact diagram and I am using a 9 volt battery as the power source. When I turn the power on and test the output of the curcuit that would be going into the diode it only says that it is giving me 0.9volts when the potentiometer is at the highest resistance and 1.5v at the lowest resistance.
If the Laser diode needs at least 4v to power up, then How is this supposed to power it correctly?
Electorials (author)  merkindesr4 years ago
The LM317T can't work without the diode (or another testing resistor) in the circuit.

If you replace your diode with a volt-meter, the LM317T is not connected to the ground, and no current can flow. (the "output" connection must have a way to go to the negative side of the battery, or the LM will simply not work).

I also think that you won't have 1.25V between Adj and Out right now because there is no diode.
If you don't have 1.25V there, it means the LM isn't working correctly because it's supply voltage isn't high enough (so, because there is no connection to the negative side of the battery).

You can replace the diode with a 100ohm resistor, and measure the voltage over it. This will fake the diode, and you can do some measurements on it. It will be quite the same as a real diode. (an LED instead of a 100ohm resistor would be even better to test with!)


You can shorten out the part where the diode should be. Since this is a current regulating circuit, it's no problem to shorten that part out.
When you do this, you obviously can't measure the voltage there, but it's good for testing if you get 1.25V between Adj and Out. You can then also measure the current going from Out to the ground - trough your diode (shortened connection) if you would like to.
aight this might be a dumb question but would there be a way to rig up a capacitor for a "starwars blaster" effect? i suppose it wouldnt really burn anything since you have to hold the laser there for a bit. idk :/
Electorials (author)  The_Black_Hole4 years ago
I think it would be possible if you place a capacitor in series with the safety resistor. (between 'out' and 'adj' pin of the LM317T).

The capacitor would need to be one with a high capacitance, and it would also need a resistor over it (in parallel) so that it's also able to discharge.
so, this wouldn't burn images into wood?
Electorials (author)  dr.knowitall4 years ago
No, you need a CO2 laser for that.
objects used to burn
Electorials (author)  lgonzalez mejia4 years ago
What do you mean?
your hand does not burn when touched
Electorials (author)  lgonzalez mejia4 years ago
No, it doesn't get hot.
malcolmpaul4 years ago
I am wondering if this can be used to rid oneself of toenail fungus.
Electorials (author)  malcolmpaul4 years ago
Bzzzzoom!! And away goes your nail!

hehe, I have no idea.
How do you make your laser warning labels? I use safelasers.org to create mine, but yours looks considerably better.
Electorials (author)  montymintypie4 years ago

My lables are just pronted with a regilar HP printer. Though they lool really good!

The only problem is that if you rub yor hand on the lables, they become dirty :(
I should use shiny paper

jdougherty24 years ago
About how long does it take for the laser to start burning? I notice you're shining it on your finger in a couple pics, so i'm guessing that it takes a bit. Also, would this sort of setup be decent to attach to a CNC machine for at-home laser cutting, or is the laser not quite powerful enough?
Electorials (author)  jdougherty24 years ago
The laser I'm using in those pictures is a DVD reader diode. It does't get warm.

This setup (electrical) would be good for a CNC cutter. The mechanical setup (the project box) wouldn't be handy.

If you get a powerful diode, you could use this tool for cutting stuff on a CNC machine but it won't cut thick things.

Real CNC cutters use CO2 lasers (we're talking about certain Watts then, like a 40W CO2 laser), and the lasers in this project are limited to 1500mW.

A 1500mW can also cut things, but not thick stuff. (a CD case would be possible, to give you an idea of the thickness)
orksecurity4 years ago
Suggestion: Once you find the "ideal" position for the potentiometer, you might want to consider using a drop of fingernail polish to hold it in that position, so it's less likely to shift accidentally. (In lieu of glyptol, an enamel paint that's often used for the same purpose.) It'll break free easily enough when you _do_ want to turn the knob.

Also, I'd be tempted to put either the whole potentiometer, or a "trim" potentiometer to calibrate this one so it can't exceed a safe limit, _inside_ the box -- again, to protect against accidentally turning the knob that one step too far.

Nice straightforward design.

One quibble: I HIGHLY approve of the calls for safety glasses (a bright laser can do a significant amount of damage to eyes with NO warning) ... but I wish folks would point to sources for glasses suitable for each frequency range. I'd also recommend that folks using these seriously consider "beam stops" -- barriers to ensure that there is Absolutely No Way the laser beam can reach anyone else, in any direction (including by reflection, and including overhead).
Electorials (author)  orksecurity4 years ago

I had an extra safety potentiometer on my previous laser burner. (with exactly the same function as you say).

I don't know why, but I just really forgot to add it to this laser too :/
I'll probably change it in the instructable. Thanks for reminding me of it!

Putting the potentiometer inside the box might be a good idea but I more like to be able to adjust the intensity without opening up the box.
(The extra potentiometer inside the box you said, makes this unnecessary).

"I wish folks would point to sources for glasses"
I don't really know what you mean with that, do you mean the sources for where you can buy them? (because I really have no idea).

Also, how does a 'beam stop' work? I don't have it, and I can't find good information about it on google because I find many different systems that are caled 'beam stops' :/
Beam stop: Essentially just a matter of, while you're setting up whatever you're using the laser for, make sure that the beam, and any possible reflection or refraction, hits a solid object before it hits anything you don't want it to hit. Good safety practice.

Glasses: Yes. Everyone -- myself included -- keeps pointing out that they're a good idea but none of us -- myself included -- provides specific examples of which glasses are appropriate for which lasers or where you can get them. One of us should doublecheck exactly what the frequency ranges are of each of these common "rescued" LEDs and provide examples of what to order and what to websearch to find them. Llab safety suppliers generally do sell these in onesie-twosie quantities are fairly reasonable prices; I bought a pair of cheap plastic UV-blocking safety glasses MANY years ago... but you need to know what to order.
Electorials (author)  orksecurity4 years ago
Tomorrow I'm going to look up stuff about these safety glasses. Types of glasses, how they work, which ones to use for which lasers, ...
I also don't know a lot about them. I'll tell you what I found.

check out Thor Labs they are expensive but at least they are certified. http://www.thorlabs.com/NewGroupPage9.cfm?ObjectGroup_ID=762

Also make sure you know what wavelength the laser diode your are using is:


DVD uses a 650 nm wavelength laser diode

780 nm for CD


405 nm for blue ray
Electorials (author)  rkey4 years ago
Thanks ;)
Electorials (author)  Electorials4 years ago
There's not much to find about how they actually work.
I als don't know where to buy them in my country.

Which glasses for which lasers I did find.
Most laser safety glasses work by blocking a certain frequency range of light. You pick the glasses which block the frequency of your laser and you should be protected. If you (as a test) shine the laser through the glasses, they should block the beam, although with that high power of a laser, you might damage the glasses by testing this.
Electorials (author)  killersquirel114 years ago
Yes, but how does that 'frequency blocking' work?
Same way sunglasses block UV rays. The laser safety glasses are just blocking the spectrum of the laser, instead of the spectrum of UV.
Electorials (author)  ryanmercer4 years ago
but do you know how a piece of coloured plastic can block a certain frequency?

Is it special plastic? A special coating? Just coloured plastic with nothing else? ...
Same way any other optical filter works... and there are many methods of doing it. Go read the wiki article on optics filters http://en.wikipedia.org/wiki/Filter_%28optics%29
A really lovely old teacher I used to have tried to instil into his students that accidents don't ask if they can be allowed to happen. He also said that you should/must arrange your workspace so that safety is built-in. In his memory, (and I do think of him and thanked him) I have safety glasses in a pouch hanging from the lock on my tool-box, safety glasses in my PPE (personal protective equipment) box which is the very first box I must touch before I can access the other boxes and safety glasses in my other storage space for gardening tools.

Thank you, kind Sir; there are many people who have you to thank for their continuing use of eyes and limbs. I shall continue to spread your wise words and wise work.

I applaud Orksecurity's words. If there's only *one* item of safety equipment you buy, make sure it's the right glasses/eye-wear protection. It's great fun to do great projects, so let's all keep it that way.
gwhizz4 years ago
Hi Electorials,
Can I use a 7805 instead of the LM317T, as I have some lying around?
Electorials (author)  gwhizz4 years ago
Hello gwhizz,

It is possible yes.
That voltage regulator can also be used to regulate current, and with a maximum current of 1A it's no problem.

You'll have to change the safety resistor of 5ohm with one of 20ohm.
The potentiometer may stay at 100ohm.

I've added an graphic for you with all things you need to know.
Many thanks
Electorials (author)  gwhizz4 years ago

I'm really sorry but it looks like I did something wrong with the previous calculations :/

I have 3 suggestions:

- Imax = 340mA - 2W 15ohm resistor - 220ohm potentiometer (picture 1)
(great burning laser. Disadvantage is that you need a 2W resistor. If we would use a smaller one, it would burn instantly).

- Imax = 280mA - 1.5W 18ohm resistor - 150ohm potentiometer (picture 2)
(medium laser but still a 1.5W resistor :/).

- Imax = 180mA - 1W 27ohm resistor - 100ohm potentiometer (picture 3)
(disadvantage: weak laser).

Conclusion: it's possible with a 7805 but we need large resistors. Your battery will also drain faster.

You'll have to choose which of the three you want ;)
Electorials (author)  Electorials4 years ago
Electorials (author) 4 years ago
Current-limiting resistor changed to 3.3ohm. Read step 4 for more information.
kangooooooo4 years ago
This is exactly the level of quality for an ible on lasers I was looking for!

Thanks a lot Electorials.
Electorials (author)  kangooooooo4 years ago
Thank you!
francisroan4 years ago
hey i have a cd reader and.......u told that have ir diode which is low power so does it burn or atleast burst a balloon within secondss??????
Electorials (author)  francisroan4 years ago
I haven't tried CD reader diodes yet. All I know is that a CD burner diode does it easily.

I don't really think it's going to work but you could give it a try :)
chaddv794 years ago
would this work with 532nm green laser diode?
Electorials (author)  chaddv794 years ago
Yes ;)
PS1184 years ago
What kind/how thick of stuff can you burn with it?

Also, since you asked, I'd like to request pics/videos of this thing in action!
Electorials (author)  PS1184 years ago

The intensity of the laser depends on what diode you are using. I currently don't have a good diode, I'm using one from a DVD reader.

It's already very bright but I know a DVD burner diode would be even 10 times better.

so if you're asking what thickness of things it can burn, I don't really know that yet.
but again, it really depends on the diode. If you can find an epic diode, you would be able to burn trough cd cases very easely.

the best diode for burning I could test with was the infrared cd burner diode from the pictures in step 6.
It can cut electrical tape.

The laser was designed for epic diodes. It can (if you find such a diode) deliver 1000mW of power for a diode, and beleave me, a 1W diode is really bright!

I'll be posting pictures or a video for you, but I can't right now because I'm not at me pc, and tomorrow I'm not at home.
So in 2 days I'll grab my camera for you ;)
Electorials (author)  Electorials4 years ago
Ok, I've added some pictures for you in step 11.

I know the diode isn't really cool, it's just a DVD reader.
It's still very bright though.

When I get my DVD burner diode I'll post new pictures ;)
kgrewe4 years ago
First off nice job. I haven't looked through the whole project yet but I really appreciate all the pictures so far. It takes more time but it really helps a beginner like me understand. Thanks for the work.
Electorials (author)  kgrewe4 years ago
No problem, Thanks ;)
rimar20004 years ago
This is very interesting, thanks for sharing.
Electorials (author)  rimar20004 years ago
Thank you!