Bridge Rectifiers

[AjohnwParticipant @ajohnw51620]

Doh – the link doesn't explain it's inherent ripple rejection – pity really as it's one of it's major advantages along with the relatively simple circuitry needed.

John

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[Anonymous]

Posted by Russell Eberhardt on 18/03/2016 11:56:35:

Most cheap DVMs respond to the mean of the modulus of the input waveform when on AC ranges. They are however calibrated to read the result as the rms value when given a true sine wave. So they are neither one thing or another.

Better DVMs have a true rms reading.

Correct.

Many DVMs use an integrating ADC, so while they are a sampled system they do not work in the same way as conventional sampled systems where a 'snapshot' of the signal is taken at each sample.

Integrating ADCs work by feeding the input into an integrator for a known number of clock cycles. The stored signal represents the integral of the input over the sampling time. Then a known reference voltage of opposite polarity is applied to the integrator and the number of clock cycles needed to return the integrator to zero is counted. By comparing the ratio of sampling clock cycles to the reference clock cycles the voltage ratio can be determined. Since the reference voltage is known the input voltage (or at least its integral over the sampling time) can be determined.

Andrew

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