EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: komrad2236 on February 16, 2023, 12:09:30 pm
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Hi guys, can you tell by looking at this circuit from multimeter, what does LM358s dual op amp do in this circuit ?
What is its job ?
(https://i.ibb.co/1TV9ZhZ/IMG-1250.jpg)
(https://i.ibb.co/hRC0KXp/IMG-1246.jpg)
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Very likely OPA is a current sensor amp, with gain 20-50. See big R010, trace connection to the inputs of the IC.
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I would see what exactly it's attached to, that might require a 2nd DMM. Then just make the op-amp circuit in a simulator. It could just be some buffer, or control circuit even too. Some DMM's like mine have a few op-amps. I traced out part of the schematic, the dial sure makes it a nightmare.
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I would see what exactly it's attached to, that might require a 2nd DMM. Then just make the op-amp circuit in a simulator. It could just be some buffer, or control circuit even too. Some DMM's like mine have a few op-amps. I traced out part of the schematic, the dial sure makes it a nightmare.
Just a note that it would require a second DMM. Nasty things happen if you start probing the internals of a DMM with its own probes. Battery -ve isn't the same as common for instance, there are offsets and internal regulators that get shorted. Even Fluke meters get destroyed by people trying to use them to measure their own battery voltage.