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Friday, April 5, 2024

Build a DIY DC Dynamic Load Instrument


The conclusion of a very long time investigating the building of a combined AC-DC Dynamic Load (DL) led me to the realization that this is not really possible. At least not without making drastic compromises about accuracy and precision. The AC measurements do not need to be very precise and are, in my case, only occasionally needed, but DC measurements typically need to have the highest precision, stability and accuracy.

The attempts for this combined AC-DC DL are described in another Blog post. There is a lot of information there, so get some fresh Java and have a look.

The above picture shows the status of the last developments, with this AC-DC DL prototype as the basis.

To help design this new version of the instrument, I asked for the help of my friend Bud. He is a real designer, and we've done a number of projects together, also described on this Blog, like the VBA Curve Tracer and the Differential Probe.

He started a Blog post on Hackaday that can be found here : Dynamic Electronic Load |

At this moment, we have finished the design of the new version and the board is in production at my sponsor PCBWay.

I'm still working very hard on the software side, because this instrument will do some things a bit different, compared to many other DIY designs.

I'll explain that later in more details but here are two pictures to hopefully wet your appetite:

The initial target specifications:

Input voltage: 1..100VDC

Reverse polarity protection to -100V and a 15A fuse.

DUT disconnect by a relays

Maximum current of 10A @ 40V (needs to be verified)

Maximum power 150W (needs to be verified)

Volt Accuracy: 0.2%

Current Accuracy: 0.6%

Power input: 12VDC Wall-wart 1A with reverse polarity protection to -24V and PTC fuse

CC, CV, CP, CR and Battery discharge modes.

GUI: 128x128 OLED 1.5' color display and rotary encoder

Temperature controlled fan

More later...

If you like what you see, please support me by buying me some Java:

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