How do I start this problem? (diode circuit)

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    Circuit Diode circuit
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Discussion Overview

The discussion revolves around a homework problem involving a diode circuit, specifically focusing on finding the output voltage (Vo) and drawing the corresponding waveform. Participants explore the implications of diode characteristics, transformer properties, and the relationship between input and output voltages in the context of AC signals.

Discussion Character

  • Homework-related
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants express uncertainty about how to find Vo and the waveform, indicating a lack of clarity in the problem statement.
  • One participant notes that the diode voltage drop of 0.7V applies as soon as current flows through the diodes, suggesting that this is a critical factor in determining Vo.
  • Another participant highlights that the secondary voltage of 1V rms is specified without the diodes, prompting a discussion about how this affects the output waveform.
  • Some participants propose that the output voltage Vo could simply be 1Vrms, while others challenge this by stating that the diodes limit the voltage to 0.7V.
  • There is a suggestion that the problem may involve unclear assumptions regarding transformer impedance and its effect on the output voltage.
  • One participant suggests that the diodes are connected back-to-back, which influences how the voltage drop is calculated.
  • Another participant summarizes that there are at least two correct answers depending on whether the transformer is ideal or practical, indicating the complexity of the problem.
  • There is a discussion about whether the output waveform would resemble a rectified sine wave or another form, reflecting differing interpretations of the circuit behavior.

Areas of Agreement / Disagreement

Participants do not reach a consensus, as multiple competing views remain regarding the assumptions about the transformer and the behavior of the diodes. The discussion reflects uncertainty and differing interpretations of the problem.

Contextual Notes

Participants note that the problem lacks clarity regarding the transformer impedance and whether it should be considered in the analysis. The assumptions about the ideal versus practical behavior of the transformer and diodes contribute to the complexity of the discussion.

  • #31
servehover said:
Would it go from 0 to 0.7 or -0.7 to 0.7? I really don't understand the problem(s) and neither do any of my classmates.
The thing you need to see is that the diodes are "not there" if Vo is between - 0.7V and + 0.7V. So for that range of Vo you get just the sinusoidal output voltage 1.414sin(wt). But as soon as Vo > +0.7V or < -0.7V, Vo has to stay ("is clamped") at those voltage levels. Now try to reconstruct what Vo must look like over an entire period.
 
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  • #32
servehover said:
If there is no series resistor in my problem (it is parallel), does that mean there is no clipping in my problem?
Yes. There is no clipping.
servehover said:
Can you explain this?
Say your input is 1V rms. If the diode is maintaining 0.7V across it, where is the remaining voltage? It has to appear across the series resistance. That means, without the series resistance, all the voltage would appear across the diodes and there will be no clipping. If there is a series resistance, the diode almost maintains 0.7V across it and the remaining voltage appears across the series resistance.
 
  • #33
rude man said:
The thing you need to see is that the diodes are "not there" if Vo is between - 0.7V and + 0.7V. So for that range of Vo you get just the sinusoidal output voltage 1.414sin(wt). But as soon as Vo > +0.7V or < -0.7V, Vo has to stay ("is clamped") at those voltage levels. Now try to reconstruct what Vo must look like over an entire period.
So it'd basically be a sine wave that is cut off beyond 0.7 and -0.7.
If this question is a trick question, the answer would simply be Vo = 1Vrms right?
 
  • #34
cnh1995 said:
Yes. There is no clipping.

Say your input is 1V rms. If the diode is maintaining 0.7V across it, where is the remaining voltage? It has to appear across the series resistance. That means, without the series resistance, all the voltage would appear across the diodes and there will be no clipping. If there is a series resistance, the diode almost maintains 0.7V across it and the remaining voltage appears across the series resistance.
So just to be confirm:
There is no series resistor in my circuit (it looks parallel). This means that the output voltage is simply 1Vrms...?
 
  • #35
servehover said:
So just to be confirm:
There is no series resistor in my circuit (it looks parallel). This means that the output voltage is simply 1Vrms...?
I would say yes..
 
  • #36
cnh1995 said:
I would say yes..
I think I will stick to 1Vrms as I have yet to find any clipping circuit on Google with parallel resistor. Can you offer any hints for the other 3 problems?
 
  • #37
servehover said:
So just to be confirm:
There is no series resistor in my circuit (it looks parallel). This means that the output voltage is simply 1Vrms...?
There being 2 possible correct answers, this is only one of them.
 

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