Cheap burning laser tutorial

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!

Warning
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.

Comments

[prodriverex]

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]

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.

[prodriverex]

hehe.. ok I got that..
Also, can we use TTL laser diode too? Or only Linear diode for this circuit?

Thanks!

[lis.tesla]

sorry im kind of a n00b
but what do you mean
(3x 10ohm resistor in parallel)

[undress15]

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]

I have no idea where to find these in other countries :/
I bought them at my local electrical shop.

[solomonhorses]

Sick! This is my next mad scientist project! Excellent instructable!

[Electorials]

Thank you ;)

[robot1398]

will i get a laser in floppy drive

[Electorials]

No, floppy drives don't work with lasers.

[SpEcIeS8472]

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]

hi,
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.

[SpEcIeS8472]

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]

huh?
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.

[SpEcIeS8472]

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]

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.

[SpEcIeS8472]

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]

It al looks really good.
The schematic is also good but I think I'll just keep the one that I already have.

[SpEcIeS8472]

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]

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!

[SpEcIeS8472]

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

[Dreistein]

i love these instructions for the reasons that you show how to make everything and you don't need any laser module

[Electorials]

Thanks :)

[florman]

Can you pop a balloon with the laser?

[Electorials]

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.

[florman]

Is the lense a magnifier? or is it just piece of glass?

[Electorials]

It's a magnifier. :)

[Electorials]

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 :/

[hjartland]

Novice question. What about eye protection? Aren't these lasers housed in a drive for a reason?

Thank you,

And GREAT instructable!

[Electorials]

they are dangerous yes, but I can't tell much about the laser glasses because I don't know a lot about them :/

[sueman2]

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.

[tim127]

what would happen if i just used the LM317? i dont know a lot about this stuff

[Electorials]

Take a look at this datasheet, at page 12:
http://www.datasheetcatalog.org/datasheet/nationalsemiconductor/DS009063.PDF

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").

[colorex]

OK, I'm new to electronics... My store has LM317L, LM317LZ, LM317T, LM317K
Which is best?

[Electorials]

The LM317T is good ;)

[colorex]

Thanks!

[Electorials]

Could you post some pictures here when it's finished? (or when not finished yet is also good)

I'd like to see it ^^

[colorex]

BTW can't you put two potentiometers in series for fine tuning?

[colorex]

When I do this, I will share it! (that may take some time)

[Electorials]

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