Question on test loads

[LaserNate]

Hello,

I've read all the laser building threads and I still have a question about drivers. Is it necessary to have a test load if I want to to set a driver with a potentiometer? Could I just connect it to a DMM and turn up the pot until I get desired results?

Thanks.

(And yes, I've used the search button and found nothing. No flame prease )

 

[comradmax]

I've read all the laser building threads

How can you say ^that^ and then ask this question? Another way to think about it: why is everyone here using test-loads, it can't be because they haven't thought of it?..

Here is a link to one of my favorite comprehensive build threads. there are others with even more detail, search some more
http://laserpointerforums.com/f51/i-want-build-laser-thread-52972.html

 

[LaserNate]

Yes I've read that one. What I picked up is that test loads are used to see if your driver is working before risking your diode.

 

[comradmax]

Yep, that's the main reason: not to risk the diode first. You have to have a test-load in order to see the current value, do not rely on your DMM's internals. You do not need a 1Ohm resistor, you can connect the DMM in series with the test-load and set it to measure mA.

If a driver is working properly it will put the same current through 1 diode test-load as it would with 4/5 diodes like being described on the forum. You want to match the voltage drop of the test-load to that of your LD, that's why multiple diodes are recommended for this.

 

[LaserNate]

Alrighty, thanks for the help. I also found a nice set of instructions over at stonetek http://stonetek.org/shop/images/TestLoadInstructions.pdf

Just clarifying, the setup would be like this?

Power source---Driver---Test load---DMM
And my driver hooks up to the leads on the test load, and the DMM on the contacts on the bottom?

 

[comradmax]

Just clarifying, the setup would be like this?

Power source---Driver---Test load---DMM
And my driver hooks up to the leads on the test load, and the DMM on the contacts on the bottom?

I think you got it.