have a few questions about drivers

[MPlaser]

Hello,
I am pretty new to lasers and was wondering when a driver accepts a voltage of say anywhere from 9V - 16V and outputs 200 mA, does that mean that the resistors in the driver will "turn on" according to the voltage from the batteries? I'm wondering because I built a Blu-ray module using a 101 mA driver and supplied 6V and then 12V and it still output around 100 mW.

Thanks in advance,
Mike

P.S. If anyone could explain to me exactly how it works, that would be great.

 

[chipdouglas]

A few questions for you MP. How do you know it is putting out 100mw? Do you have an LPM? Now a short explanation. Laser diodes work of off current, in this case ma (milli amp). The LD will draw an infinite amount of current till it blows, that is where the driver comes into play to preset a max amount of current. usually drivers have a potentiometer to allow you to adjust the current to a level that you desire. Now the driver itself uses voltage also. I hope this helps a little.


michael

 

[MPlaser]

Ahh ok, does help a bit. I followed styropyro's video on youtube as to how to make it and he suggested I used specific parts, one being a driver with a fixed current of 101 mA which would allow the diode to output (according to him) 110mW of power. As for the potentiometer, how would I know what the current is currently at?

-Mike

 

[chipdouglas]

to make a test load use this link http://www.laserpointerforums.com/forums/YaBB.pl?num=1240637315/0#0 then scroll down to the second drawing in the white box. you use this set up instead of the laser diode to preset the current. when you have the test load hooked up to your driver, connect the batts and your DMM set to milli volts. mv in this set up should equal ma, so turn the pot slowly to your desired mv/ma. make sure you short the capacitor on your driver before reconnecting your LD OR YOU WILL FRY IT!! :-/

michael

 

[rkcstr]

Laser diode drivers are a little more complex than some resistors.  A resistor will act as a "current limiter" in series with a load (connected between the battery positive and the diode positive, for instance), but how much current will pass depends on the voltage of the battery and the diode's voltage and the resistance.

Now, a driver for a laser diode will use active electronics to precisely put out a current over a range of voltages and conditions (hence regulated current).  So, it is meant to put out the same current no matter the battery voltage (within its limitations) and possibly the output voltage as well.

As for measuring the setting on an adjustable current driver, that will partly depend on what driver it is, but as suggested, hooking up a dummy load (something you won't have to worry about damaging) and using that to measure the current with a multimeter (actually measuring VOLTAGE and calculating current). There are other ways too, but that one is probably the simplest to understand.

 

[MPlaser]

Great thanks for the advice guys!!

 

[Meatball]

active electronics? I've always wondered what that means... does that just refer to the components inside the IC? I've always wondered what goes on inside one of those little packages.... as far as I know, it's magic! Voltage goes in... regulated current comes out! What happens inside the IC? What are these active electronics?

 

[bhank]

Hey guys. I'm pretty new here, this is my first post. So I've been trying to find information on drivers but I'm in the same boat as MPlaser, only I need a little more detail. Could anyone help me out and explain to me the basics or give me a link to something that would help?

Thanks