Dave grabs a few junkbox parts and builds a useful constant current load for switch mode power supply, battery testing, and other applications.
Eevblog #102 – diy constant current dummy load for power supply and battery testing
ByYTB
Aug 1, 2010
Ramen
Regarding testing 18650 cell : Who is right ? – the people that set the cutoff at 2.5V. or 3.0V. – I see on youtube that some test 18650 battery with different cutoff – then the result will also be different !
Hello – can you suggest how I may use this to test multiple outlets on an industrial PDU.
Since MTP3055 is an N channel mosfet, shouldn't you put the load resistor on the drain side? Or does it not matter in this case? I'm trying to replicate something similar with constant power mode as well
HEY DEAVE, WHAT A BOUT A NEW VIDEO LIKE THIS, WHAT'S NEW IN POWER SUPLY TESTING!
excelente video…. aca un nuevo suscriptor…. saludos desde Yaritagua Venezuela
Great video. Can you suggest equivalent of cx101?
The other part of the heat dissipation calculation is that the MTP3055 has a thermal resistance between junction and case of 3.13 degrees C per Watt. That means with your 11 W example, that the mosfet junction will be another 3 x 11 = 33 degrees above the case/heatsink – a little over 100 degC with a 20 degC ambient. That's within the maximum operating temperature of 175 degC for the device, but a little toastier than I like.
The corollary is that your heatsink/mosfet combination has an absolute maximum power dissipation of around (175-25)/(4.5+3) = 150/7.5 = 20 W with a 25 degC ambient. You might want a better cooling solution if you start looking at higher voltages and currents – 12 V and 2 A would well exceed the capabilities of that heatsink. And to get past 50 W, you'll need a mosfet in a different package.
The intro is so 2009 😅
Nice on tho, exactly what i was looking for
Thanx for sharing you knowledge, you're amazing!
you are awesome dave dada(dada means brother in Assamese language)
Can I get the PCB design and BOM to implement it in a holiday DIY project?, Thank you.
just what i was looking for
Hi Dave,
Thanks a lot for this video.
Do you think that we also could develop an AC version of an electronic load. I know this would be a complete new design. Please let me know your opinion. Best regards from Switzerland, Rene
thank you so much. you are the best!
Will something like this work for testing amperage and voltage at same time on a solar panel with a watt meter? If not could you please make a video of one that would do so for A47 volt panel or higher?
Very well explained and executed.
…If you'd only gone one step more and shown how to relate the allowable maximum temperature of the MOSFET to the power dissipation of the heatsink to verify that the heatsink would adequately protect the MOSFET for the maximum current you were allowing the device to draw.
You are drawing that mosfet wrong. Is it an enhancement mode or a depletion mode device?
But if you turn your 10 turn pot all the way to 0 you have a short!
Thanks for your videos! I'm trying to learn Constant Current Dummy Load, but I need little more info, so I can make one based on your design and try to make my own – that is how I learn. Anyway, is there a video that shows the exact schema and the parts list? Or did you make one that is more sophisticated with a better LCD display? Or anyone else who knows, can you just post it here or send me a reply. Thanks in an advance to you all.
Just stumbled across this in 2020