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  • Author Author: Matt
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Measurements with an SMU - Workbench Wednesdays 40

 

Source Measurement Units, or SMUs, combine an accurate power supply, high-power electronic load, and precise digital voltmeter into a signal unit. They are a four-quadrant source. That means they can provide power to a circuit or consume it. With an SMU you can characterize semiconductor devices (like Diodes), monitor the power consumption of a circuit, or simulate a battery. In this video, see the difference between an SMU and a Power Supply.

 

Supplemental Content:

Bill of Material:

Product Name Manufacturer Quantity Buy Now
NGU401COM - Source Measurement Unit (4-quadrant) Rohde & Schwarz 1 Buy Now

 

  • in reply to koudelad

    Hi David,

     

    There's a half-complete project here too, which was supposed to be a battery simulator, but unfortunately nowhere near as flexible as a real SMU : (

     

    Building a Battery Simulator - Part 1

    Building a Battery Simulator - Part 2

    Building a Battery Simulator (Project Morpheus) - Part 3

    Building a Logging-Capable Power Supply

     

    That last link used the board to make a PSU, where in the comments there, there's a screenshot there where I tried to do current-limiting in software, and that worked, so it's just another step to try to implement an internal resistance in software that can vary as the battery depletes. Actually modeling a real battery closely is another matter, but that's feasible too.

    It needs more work, but the board seems to function with no known issues so far, but it's still a coding exercise to get it to do more (I used Mbed for it so far).

    If I was to do it again, I'd extend the supply voltage and current range a bit, but it was only intended for IoT type sensor devices (single Li-Ion/Li-Po or dual AA or coin cell for instance).

     

    Video of the PSU:

  • Nice presentation, thanks! It looks like this device would work perfectly as a battery simulator. I checked prices of used models and they are out of an amateur price range.

     

    However, there is a learning tool with SMU-like functionality I got recommended on the Roadtest page of this SMU. Check this out: https://www.element14.com/community/roadTests/2307/l/rohde-schwarz-ngu401-source-measure-unit#comment-278560

  • Very good show.

     

    I now know how to use and SMU.

     

    DAB