How to make a selectable Dummy Load - VERY in depth

Hey guys,

I get a lot of questions about dummy loads, common examples are "How much do they cost?" "How do you make them?" "How do you use them?", so I decided once and for all to make a VERY in depth video tutorial explaining what you need, what it is used for and how to use it.

First off... I changed the design halfway through the tutorial and forgot to mention it.... the anode and cathode direction of the diodes were swapped due to poor PCB layout planning on my part.

This is a DIY super cheap, laser driver selectable dummy load. Each diode has its own dropout voltage of about 0.75v which makes this a total of 5.25v max dropout voltage.

Components used
1 x 1ohm, 1watt resistor
16x gold plated header pins
7x 1n4004 diodes, 400v 1A max
Protoboard with separate copper pads for each hole.
Total cost ~$13

Can be used for any laser diode available, from IR to blue laser diodes.

Finally here is the video...


I made a crappy diagram of how its meant to be wired up.... in case, for some reason you didn't understand from the video...


And here are some close ups of the finished product...





Hope this helps!!
-Adrian

Thanks for posting that Adrian.

If you are using it to test more than 1A driver for say.. 445nm diode this dummy load will overheat...


You must use diodes capable of at least 2A (i use 3A 1N5408) + bigger wattage resistor ... I prefer 5W 1Ohm to keep it cool for a longer time. When you measure current on heated components it actually makes results inaccurate. Oh and the bigger the current the higher voltage drop across each diode

Pretty cool

I think this thread might be worth a sticky, i'l talk to Ave about it soon

Excellent video tutorial bobhaha. I watched most of it. I love those gold plated header pins

Very nice video ! +1 rep !

Nice Video
Found one thing: the 2.54mm from the jumpers are the gap between the contacts not the contact diameter
I hope to see more videos from you soldering...very entertaining :beer:

I enjoyed the soldering the most

It would be cool if you (or anyone else for that matter) could make a narrated soldering video

regalis said:

Nice Video
Found one thing: the 2.54mm from the jumpers are the gap between the contacts not the contact diameter
I hope to see more videos from you soldering...very entertaining :beer:

Click to expand...

Yeah it hit me after I made the video... I was like "DUHH! now I know what that number is for" but I think you get the picture.

Well done my man!!

Thank you DarkSide.

I enjoyed watching! I have a few spare hours today to head to radio shack and build one.

Thanks for taking the time to share it:thanks:

I'm going to build one myself but I would use foulmist improvements

Thank you for sharing

I wonder why there is the resistor in the dummy load at all. A protection? A position to measure voltage? If we care just about voltage drop, the resistor is redundant indeed, hm?

^It's just a more convenient way (for some) to measure current. Replacing the resistor with an ammeter is fine, too, provided you recalculate the number of diodes required.

Very good of you to make this thread :beer: