How to use a Laser diode

Hi all, I just began using arduino but I'm an electronic newbie. I did an order from futurlec.com and I also ordered the first laser in this page http://www.futurlec.com/Laser_Diode.shtml Specifications:

Red High Quality 10mW Laser Diode

Long Operating Life

Operating Voltage: 2.3V

Operating Current: 45mA

Optical Power: 10mW

I thought it was esear to use but I was wrong. After a little search I found this schema It is usable for my laser too? What is the resistor value to use in my case? Thanks

p.s. multipost in Arduino Forum ? International ? Italiano section Obviously I'll merge all the answers from a thread in the other

Sorry, I haven't understand your answer. Do you mean you don't need any other component? Could you please explain it to me?

My only concern would be that he states his module requires 2.3V, where the circuit has 3.3V or 5V (from the Arduino) powering the module. Running at 5V may be possible, but it might shorten the life of the laser module (having a real spec sheet might help).

According to here:

http://www.arduino.cc/en/Main/ArduinoBoardDuemilanove

The 3.3V regulator can handle a max of 50 ma of current; 45 ma seems to be cutting it close…?

I think an external supply capable of supplying 2.3V and 45 ma of current may be called for; the control circuitry, though, can stay the same.

Ok - wait a minute - he's referencing the laser -diode- offered on that page - not the laser MODULE. A laser -diode- is going to need a little more than that circuit to operate properly (without it burning out); it needs the proper voltage and current control...

What that circuit shows that the OP posted is a control for a laser module, but shows a diode in place of the module (which is incorrect). The OP is referencing the data for the diode on futurlec's page - which is not what is called for in the circuit.

The OP should either use the laser -module- that futurlec sells on that page, or investigate how to properly build a power supply for a laser diode (which can then be controlled by the circuit already posted).

Simple laser diode supply schematics can be found here:

http://www.repairfaq.org/sam/laserdps.htm

...and here:

http://laserpointerforums.com/f42/diy-homemade-laser-diode-driver-26339.html

...among other places on the net (google "laser diode driver").

You might consider adding a resistor in the power supply that will limit the current to 45ma when connected to a 5v power supply instead of the 2.3v. Probably depends on the assumptions made in the specs.

Many thanks for your advice and answers.

From one of linked site I got this schema: From what I understand,: - to get my 2.3V I have to replace the 4 ohm resistor with a new one, how to calculate the right value? - The pot (variable resistor) is to vary the voltage to the laser, if I always need the same voltage I can omit it. - The purpose of diode is to provide reverse polarity protection. - what is the purpose o capacitor and how to calculate the value I need?

Many thanks

I can't read anymore until 27th december. Happy Christmas to everyone