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Author Topic: Differential Connections analog input  (Read 1007 times)
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Hi

I have to measure the voltage drop over a shunt. It gives 60mV return when full current is passing. I want to measure it with the arduino. So here is the problems i cant really find a good solution for.

The power supply is not the same as the arduino. So i will have to measure it "like a voltmeter" - What op amps can i use to get a higher voltage for the arduino and be able to measure it correctly?

I will also need a higher ADC then the 10bit. Any suggestions that could help solve this project? Needs to be 14-16 bit. I have been looking at adafruits ADS1115 but is out of stock at the moment.

This is my idea;
Analog read max 60mV -> Some kind of gain -> ADC 16bit > Arduino

But really cant figure out what components is out there that will solve my problem.

Regards Mark
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Manchester (England England)
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You need an op amp powered by a supply that is higher than the voltage you are trying to measure. What is that voltage and what is the real current?
If it is high then there are hall effect current probes you can use without an op amp.
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The current is 50A. But in a later project could go all the way to 200A. Power supply is 24DC.

I dont have to measure it right now but the current can pass either way.
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The voltage i am trying to measure is only 60mV. Forgot that part.
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You would be better off with a current sensor, see:-
http://uk.farnell.com/jsp/search/browse.jsp?N=2031+203849&Ntk=gensearch&Ntt=current+sensors&Ntx=mode+matchallpartial
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Set your ADC V reference with external high precision reference. While you need external ADC, use LTC2473 16-bit differential ADC. Common problem on low voltage measurement is weak signal to noise ratio.
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