How to drive green laser using an Arduino

That was a really fast response man!
Thanks a lot!
I have a 4007 diode here in my box. Is it ok to try with this? Or should I wait tomorrow to buy the 4001?

OBS: About the laser: it is a 1W green laser pointer (at least it states that in the label, but since it is from an unknown chinese manufacturer, who knows... I dont have the pro equipment to certify that - Is there a way to discover how many mW it has for real just by measuring its current?)

About the driver: it seems to have one inside, but I cant tell you exactly what's included with it...

All I know (tests I made) is that it worked with 3.3 volts and 4.5 volts (at least for a couple seconds without blowing up) using my DC power supply, showing 180mA and 530mA respectively in the multimeter.

No problem!

Yes a 1N4007 should do fine, the higher the last number the higher the current it can handle.

No, you can't determine optical output by input current, the process is nonlinear and very inefficient with variable efficiency.

The reason it drew more current at the higher voltage is because the lower voltage was not sufficient to fully forward bias the pump diode. The circuit I drew above will supply 4.3V at whatever current the driver needs, which is perfect - not too much voltage, not too little, and it should draw less than 600mA so the 2N2222 is good.

Sigurthr said:

The reason it drew more current at the higher voltage is because the lower voltage was not sufficient to fully forward bias the pump diode. The circuit I drew above will supply 4.3V at whatever current the driver needs, which is perfect - not too much voltage, not too little, and it should draw less than 600mA so the 2N2222 is good.

Click to expand...

That is incorrect. These green laser drivers use the following schematic for a driver:

Basically, that is a LM317/1117/whatever EXCEPT it does not have a reference voltage (1.25V) and works as a current sink, but instead the + of the op amp is connected directly to input voltage, thus making these linears have a reference voltage not 1.25V but the voltage you connect them to. The equation for calculating the current is "Io = 1 amp/volt Vin" with a 1 ohm resistor, thus meaning it gives 5A at 5V. I have already investigated a O-like 200mW green module with Brandon, and that one has 7 Ohm resistor, thus giving 600mA at 4.2V. Now, it is VERY dangerous to connect them to a higher voltage than they were intended for, since you are basically pot-modding them. Ever wondered why china lasers get dimmer with less battery and Flexdrive or DDL homemade ones don't? Exactly beacuse of this. As the battery discharges, it's voltage drops and lower (reference) voltage means less current. Several members have reported these modules dying very soon when connected to 5V. 4.3V should be safe though.

Sigurthr said:

No problem!
Yes a 1N4007 should do fine, the higher the last number the higher the current it can handle.

Click to expand...

Just a small correction.... The current for this series will always
stay the same at 1Amp.

The higher the number 4001 - 4007 the higher the breakdown
Voltage (PIV).

4001 = 50V
4002 = 100V
4003 = 200V
4004 = 400V
4005 = 600V
4006 = 800V
4007 = 1000V

Jerry

Like Jerry said. If you are looking for a diode that handles more current, try the 1N540x series. These do up to 3A.

Yep, I have a bad habbit of posting late at night, thanks for the corrections! I did indeed mean inverse voltage, not current.

Also, good to know about the kind of driver - I've never run in to any of them myself in all the cheap greens I've had. Output brightness has always stayed stable from 2.4v all the way up to 3.4V (1.2 to 1.7V per cell) in all the greens I've ever had. Well, my 4.3V schematic will still work fine as Johnyz said.

I would like to thank again all my friends here at laserpointerforums.com!
I stayed all night trying to make it work and here are the results:
1) At first it did work but the light was very dim.
Latter after some tests I found out that the problem was Arduino programing... :evil:
2) I made some tests with basic blink programing and then it DID WORK!
Laser shines great and as it should be!
I custom made a blinking program with delay going from 500ms until 5 ms and it did work all the way.
3) Then I switched to my complete Laser Harp program and the laser shined dim again...

Now that I isolated the problem, I've got to work at Arduino programing to find out what is the problem there and then fix it...

I guess I now will have to post some comments on Arduino.cc forums.

I promisse to come back as soon as it is solved and post all my experiences and results for my laser loving friends be able to share this journey and have lots of fun with it!
Yes the Laser Harp will play for real! And it will be open source!

For those oof you wondering what the hell is a Laser Harp here is a Youtube video preview:




If the above video does not play here is the link:

http://www.youtube.com/v/lOdHCMOe7kc?version=3&

P.S.:Can somebody tell me how to embed a Youtube video in this blog?

P.S.S. THanks to Sigurthr tip now Youtube videos seems to apear correctly! Finally! :wave:

To embed a YT video you only need the video ID part at the very end of the link, not the whole link.

Thanks Sigurthr!
I love the internet and the concept of open source colab thinking!
It seems we have no limits to where we may end up....
Cheers!

OK, I love numbers with "7" and this post was 70770...
I was very sad to leave this but... it seems now its time to start a new post, with a title named:

Laser Harp (Open Source):

http://laserpointerforums.com/f51/laser-harp-open-source-71149.html#post1025132

Please follow it with me!
Time to give it back for all of you!
Thanks!

After a lot of tests, trial and error here is what I have:

I am using the 2N2222 to blink the laser.
It works but I have found out that the laser light shines dimmer than when I use the original batteries without the 2N2222 in the way.
So I would like to replace the 2N2222 with something similar that could send more current to make the light brighter as when I use only the original batteries.
What would you recommend instead of the 2N2222?

OBS: I am not using an external power supply to drive the laser pointer anymore. I am using the original battery (3.7 v).

here is the fritzing drawing:

The reason the laser is dimmer with the battery and 2N2222 is either because there is a dropout voltage across the transistor or because the maximum current the 2N2222 can pass is 600mA. Measure how much current the laser is drawing by connecting a multimeter set to the 10A range IN SERIES with the battery. Don't use any other parts of the circuit, just the laser and the battery and a multimeter. If it reads less than 600mA the current cap of the 2N2222 is NOT the problem. If it reads >600mA you need a different transistor.

If the above test was <600mA then you have a voltage dropout issue. Just like there is a dropout voltage across a LM317 regulator when we make drivers with them, the same idea applies. You lose between 0.7 and 1.4V across the transistor. This happens whenever you use silicon based active components. There isn't really any other easy/cheap alternative, no matter what you put in there you'll get a voltage drop that you have to deal with. The solution is to apply more power. Replace the 3.7V Li-Ion (which is actually 4.2V) with that 5V 1200mA power supply you were using earlier, or with 4x 1.2V NiMH cells in series, or 4x 1.5V Alkalines in series with TWO forward biased 1N4001 silicon diodes.

Thanks again Sigurthr. You're very kind to share your knowledge with me!

Measure how much current the laser is drawing by connecting a multimeter set to the 10A range IN SERIES with the battery. Don't use any other parts of the circuit, just the laser and the battery and a multimeter. If it reads less than 600mA the current cap of the 2N2222 is NOT the problem. If it reads >600mA you need a different transistor.

Click to expand...

The battery label says 3000mAh, but I measure like this and it was about 500mA, so I think I can stick with the 2N2222.

You lose between 0.7 and 1.4V across the transistor.

Click to expand...

How can I measure how much voltage I am losing with the 2N2222?

Replace the 3.7V Li-Ion (which is actually 4.2V) with that 5V 1200mA power supply you were using earlier, or with 4x 1.2V NiMH cells in series, or 4x 1.5V Alkalines in series with TWO forward biased 1N4001 silicon diodes.

Click to expand...

I am trying to use batteries instead of power supply now to save space, so I like your 4x1.2 NiMH idea. I'll try that for now.

No problem at all, I like to help.

If you want to measure the voltage drop across the transistor you will need to have it hooked up to your arduino circuit with the arduino set to have the laser ON, not pulsing. With the laser on you set your multimeter to measure voltage and you put one lead on the Collector and one lead on the Emitter (the outer pins). If your multimeter doesn't do polarity correction then switch which lead goes where if the meter shows no measurement. This only works when the circuit is set up so the laser is on while connected to the arduino.

Guess what? I tried those 4x1.2 NiMH batteries, but they didnt last for 5 minutes...
My original battery was also drained, so I got back to my 5volt 1A power supply...
It seems like halloween here...
Maybe because i dont like to solder things, and want to KISS (keep it simple stupid), I had some problems with bad contact conections.
After all double checked I could make the power supple work again.
It was brighter (the laser light) and worked!
Here is a video and pics of it.
FOr more datails and arduino programing check out my blog:
harplaser.blogspot.com

I cant thank enought all the members of this forum that helped me until now specially Sigurthr!
Questions and upgrade ideas are welcome.

PS. I still would like to know how can I measure how much voltage I am losing with the 2N2222?

Glad you got it working, and remember to keep those Li-Ion cells charged, they die from being discharged. See last post for voltage drop measurement.

Btw, I don't see a video link in your post.