Author Topic: Hacking a surprisingly good Uni-T multimeter. Teardown and serial com upgrade  (Read 3952 times)

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Offline paulossantTopic starter

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After seeing some multimeter teardown videos from Dave Jones, I was worried about what he shown from the cheap Uni-T multimeters, especially about thei input  protection. So... since I use one (Uni-t UT133A), I opened mine to see whats inside, and must confess I was happy to see what I've saw. check the pictures!

Ceramic fuses, PTC and varistors...


Very nice layout..


UL certified!


So.. all was good!  :-+

Next, I decided to see if the blob controller was outputting anything on the Tx Rx pads...

and connected the oscilloscope to it and.. it was output something! Nice!  :-+

Finally connected connected Tx to my logic analyzer and started to try figure it out.





After a few minutes, and google search to see any uni-t multimeter serial protocols, figured it was rs232, LSB first 8N1, 2400 Baud.. Then created a .ods file in libreoffice calc and wrote some of the outputs..
So all it is needed to use the multimeter as a datalogger is to test the Tx line, plug it into a micro and create a GUI.
Which could be easily done with a stm32f103, and create a GUI with QtPy...

Will it be worth it?  :-//

Tell me what you think!

I leave attached the .ods file with what i've done so far.
 
The following users thanked this post: coromonadalix, paulbt

Offline uer166

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It is not UL certified, it "conforms to a UL standard", but UL have never seen this meter.
 

Offline 2N3055

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It is not UL certified, it "conforms to a UL standard", but UL have never seen this meter.

ETL listing is equivalent to UL listing, and Intertek is reputable company.
"Just hard work is not enough - it must be applied sensibly."
Dr. Richard W. Hamming
 


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