Best way to connect dummy load.

Hi everyone. Just joined the forum and this is my first post.
I've been watching the forum for quite a while now and decided to join as there seems to be a wealth of information here and a lot of knowledgeable helpful people.

I would like to ask for a little info about setting up a dummy load for a blue laser diode.

The specs for it are:
Known as "M-Type M140"

Manufacture: NICHIA Corporation Japan

Color output: 445nm - Blue

Continuous optical output power: 2W +/-0.15W

Operating current Typ.: 1.6A

Operating voltage Typ.: 4.5 - 5.0V

I have a constant current driver with adjustable current and voltage and have a dummy load (string of diodes and 1 Ohm resistor).

As you can see the LD's operating voltage is between 4.5 and 5.0 Volts.

What I'd like to know is:

If I want to set the voltage to say 4.7 Volts, do I first power on the driver and set the voltage to 4.7 volts, disconnect the power and then connect the dummy load and set the current, or connect the dummy load then power on and set the voltage and current ?

This may have been asked before but I searched around and could'nt find it.
Any help would be appreciated.

Thanks.

Connect the test load, power on the driver, set current, turn off driver, disconnect test load.

Not sure what driver you have but a purely constant current driver doesn't have an output voltage setting, seeing as the voltage is adjusted by the driver to keep the current constant.

Thanks very much Diachi.

May be I should'nt have called it a constant current driver.
It's one of these:
2A Laser Diode Driver for 405, 450, 520, 635 and 660nm Diodes TTL Modulation, 12V (V2) - OdicForce

StuartB said:

Thanks very much Diachi.

May be I should'nt have called it a constant current driver.
It's one of these:
2A Laser Diode Driver for 405, 450, 520, 635 and 660nm Diodes TTL Modulation, 12V (V2) - OdicForce

Click to expand...

That is constant current. The description says "adjustable output voltage" - That's sort of true, seeing as the voltage is varied by the driver. The current remains constant at whatever you set it at with the multi-turn pot on the board.

Thanks for clearing that up. I'm greatful for any help I can get. The more I know the less chance I have of getting it wrong.
I have made a laser engraver using the method that a lot of people use, especially on Instructables website.
I used the LM317 method of a constant current device for that. It works great but I want to make a bigger one with a more
powerful laser and get it to do the sort of greyscale engravings I've seen in the net.

Thanks again.

Hi StuartB, welcome to LPF!
Since you are on the OdicForce site, you should take a look at their very own page that details the 'dummy load set-up proceedure' it's pretty informational.

That driver has a multi-turn pot and another trim pot labeled VR1. I saw this type of driver on another site and the trim pot was labeled voltage output adj. Couldn't figure out why it was there, but this might be the same thing.

Hi BowtieGuy. Thanks for the welcome.
I did see the dummy load set procedure but wanted to check here as well.
The voltage trimmer is because the driver can be used for other things as well as laser driver.

If anyone is thinking about buying this type of driver board they should check the underside of the board if possible.


This one has the Fan connection marked wrong on the underside.
It has the Fan +V pin connected to the -V or Gnd of the power input barrel connector and 2 pin power connector.

https://goo.gl/photos/drnGoyr5G7xpHKKg8

This one looks correct.

https://goo.gl/photos/MKBG5BU8LffVvciRA

Strange that all these are labeled as laser diode driver boards. That threw me when I saw the voltage adjustment pot.