Half wave vs peak detector circuit

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Discussion Overview

The discussion revolves around the differences between half wave rectifier circuits and peak detector circuits, focusing on their operational principles and applications. Participants explore the characteristics of each circuit type and their suitability for converting AC signals to DC, particularly in the context of a specific project involving sensor circuits for an autoguided vehicle.

Discussion Character

  • Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant notes that a half wave rectifier only allows positive half cycles through, delivering zero volts between those cycles.
  • Another participant explains that a peak detector holds its value and delivers a steady level equal to the peak value of the most recent positive half-sinusoid, rather than half-cycles.
  • A participant questions whether the two circuits work the same way, indicating a need for clarification.
  • It is mentioned that while both circuits may use similar components, a peak detector typically requires an op amp for practical applications to compensate for diode voltage drops.
  • One participant states that the choice between a half wave rectifier and a peak detector depends on the application, suggesting that they are not interchangeable in most cases.
  • A participant shares their context of working on a sensor circuit for an autoguided vehicle project, indicating a need for DC signals from AC sources.

Areas of Agreement / Disagreement

Participants express differing views on the operational similarities and differences between half wave rectifiers and peak detectors. There is no consensus on whether they can be used interchangeably, as some suggest they can be replaced in certain applications while others argue they are mostly not interchangeable.

Contextual Notes

Participants mention specific requirements for their projects, such as the need for DC signals, which may influence their preferences for circuit types. The discussion does not resolve the technical nuances of each circuit's performance or the implications of using one over the other.

Who May Find This Useful

Individuals interested in electronics, particularly those working on circuit design for sensor applications or those exploring rectification methods in signal processing.

onceinalifetim
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hello

I would like to know what is the different between half wave rectifier circuit and peak detector circuit..
as what i know from half wave.. it only take the positive wave only..
then what about peak detector ??
 
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The half wave delivers, say, the positive half cycles. Between those half-cycles it delivers nothing, i.e., it delivers zero volts.

The peak detector holds its value, so it doesn't deliver anything recognizable as half-cycles. Between the peaks of the AC it delivers the same voltage as the last peak. Instead of half-sinusoids, it delivers a roughly steady level, equal to the peak value of the most recent positive half-sinusoid.

For further detail, google.
 
do they work the same way? thanks for the reply
 
A peak detector should do something more along the lines of this (this one is self resetting, it doesn't need to be! it might just hold the peak, that's what 'traditional' ones do)

They don't work in exactly the same way although they have similar components. The peak detector for any practical purposes usually requires an op amp. You can build one without an op amp, but you will not detect the peak as you will lose some voltage across the diode which prevents the 'peak' from discharging. The op amp can be used to compensate the diode drop. http://en.wikipedia.org/wiki/Precision_rectifier

Please check out this thread about a peak detector build here:

https://www.physicsforums.com/showthread.php?t=713307
 

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onceinalifetim said:
do they work the same way? thanks for the reply
That depends on the application. There are places where you could replace one by the other, but mostly not.

The peak detector has already begun the process of "smoothing", whereas the half-wave rectifier shows no smoothing.
 
the reason why i ask because I am currently working on a autoguilded vechile project and am doing the sensor circuit... my PIC need DC signals.. so i need to change AC to DC.. that why am thinking to choose half wave or peak detector..
 

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