Electronics > Beginners

A peak detector that restarts (multiple peaks)

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baksuz:
Hiiiiii I new here be gentle  ;D

First to explain I have a sensor that emits output, wave with different amplitude, that is AC 5V 10kHz.
My question is: Is it possible to make a peak detector that resets it peak value every time when V = 0, for collecting peaks I am going to use Arduino UNO.


I would like to thank you for you time.
   

Kleinstein:
One could use a normal peak detector circuit and use the zero crossing as a trigger for the reset and maybe Arduino to start the ADC  conversion first.  The peak detector could be the normal way and the Arduino would trigger the reset.

With just 10 kHz a fast Arduino (ARM based) may be fast enough to use direct digital sampling and peak detection in software.

baksuz:
If was planning to use Arduino, but I have a STM32 that I believe that well be enough for ADC.
Regarding that trigger for zero crossing, which component would I use, I apologize if that is a dum question.
And during conversion I would just convert a peaks as they are coming if I am correct.

Kleinstein:
With a fast (e.g. ARM based) µC the HW would be mainly scaling the signal to the ADC range and everything else would be in software.

With the relatively slow (especially the ADC) AVR based Arduino one would likely need an analog peak detector (maybe 2) and zero detection with a comparator. The µC internal comparator would need some extra level adjustment / limiting to stay inside the operating range. It slightly depends on how the signal is relative to the µC's supply. It likely is something like some diodes for clamping the signal and a shift to bring zero signal somewhere to the center of the range.

After trigger the first thing would be reading the peak value with the ADC and only than the actual reset of the peak detector. Sampling of the ADC takes some 20 µs - so the actual reset maybe 20 µs after zero crossing. With a true AC this would be in the opposite polarity phase and thus likely enough time before the next peak. If both polarities are needed this might need 2 separate peak detectors.

baksuz:
Thank you very much for your time and your explanation, it is really helpful to me.

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