EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: jonwhite on November 21, 2016, 08:49:12 pm
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Hello I'd like to use this sensor and make a simple switch I'd like to measure the current t of a single phase and when it gets to say 200 ma output 5v wonder if anybody could point me in the right direction ie what if I component I could use that would do the job
Many thanks
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Single phase? Do you want to look at one side? Do you want average or peak? The output centers around 2.5V. A three terminal LM431 trips at 2.5V. Add a pot and you could easily look at one side of the waveform and look at the peak. A PNP transistor could then invert the signal. Or use a comparator, the 431 could be your reference.
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I want to measure an AC signel single phase and when that phase is lost trigger a 5v output
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Why 5V? Is this a micro? Does it have an A/D? Do I have to do all the work?
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The application circuits in the data sheet are quite suitable, if slightly modified. You just need a comparator after the rectified and filtered output to convert your signal from analogue to digital.
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The output from a 712 in an ac application will be a low level ac signal. That could be amplified and rectified. Something as simple as running it directly into a logic input may be sufficient for go/no go application.
I just got back to project that uses a 5A ACS712. At 200ma DC I only get 10 counts on a 10 bit A/D. Of that 4 counts are noise. And I've found these are drifty with temp. Maybe because these are cheap ebay clones. I think YOU would have difficulty using these in this application. You would be better off using a current transformer with multiple loops.