Re: Split core current transformers
Dave, It's not diode linearity that's the problem - it's the nonlinearity inherent to precision rectifiers at low voltages. This most often is caused by different cutoff voltages in the diodes being...
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Jerry, That's 2V RMS, ie. 5.65Vp-p! Just thought if you had a CT that could give you the 3Vp-p you're looking for it might simplify things a bit...
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Bill, Ah, sorry - I missed the RMS. I read it as 2V P-P. We could divide it down, but then that comes up with other problems like how to protect against overvoltage on the input. As I said earlier,...
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The accuracy of a precision half wave rectifier does not depend on the diodes. The two dominant error sources are Op Amp input offset voltage and the resistor tolerance. The circuit can be configured...
View ArticleRe: Split core current transformers
Dave, I am well aware of the inherent errors in amplifiers, especially offset error in op amps and resistor tolerances. However, I believe you are incorrect about the diodes. You can easily see the...
View ArticleRe: Split core current transformers
Given an ideal Op Amp (infinite GBP) in the circuit shown, the diode non-linear forward voltage drop is completely compensated for. The voltage at the summing junction is zero volts and that is set by...
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The ADC needs to have considerable headroom to measure non-linear loads having a high crest factor. I see some instruments designed for a 5:1 crest factor. To measure a 20 A RMS, and be sufficient for...
View ArticleRe: Split core current transformers
Dave, Yes, some instruments require a 5:1 crest factor. But that is not necessary for our usage. Additionally, we are quite familiar with the appropriate safety standards and our design follows them...
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precision rectifier for split core current transformer
If I could add a little light (and not too much heat) to this discussion, a precision ground-referenced rectifier can be made with 2 GOOD rail-to-rail op amps and no diodes, per the attached diagram....
View Articleprecision rectifier for split core current transformer
Mike, As I mentioned to Dave - the design is complete. There will be no further changes. And yes, your circuit does not require diodes - but still suffers from the same crossover distortion of...
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