Understanding Clamper Circuits: Analysis, Voltage Shifts, and Capacitor Behavior

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Discussion Overview

The discussion revolves around the analysis of clamper circuits, specifically focusing on voltage shifts, capacitor behavior, and the role of the diode in determining output voltage. Participants explore the implications of a large time constant and how it affects circuit behavior.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions why the output voltage is expected to be shifted upwards by 20V when the input is 20V, noting that the diode is reverse biased and the capacitor charges.
  • Another participant argues that with a large time constant, the capacitor does not charge through the resistor and suggests considering the behavior of the circuit if the resistance were infinite.
  • A participant expresses confusion about the implications of a high resistance leading to almost zero current and questions how to determine if a large time constant indicates large resistance or capacitance.
  • There is a mention of the voltage supply being constant, with a participant suggesting that the voltage may oscillate between +20V and -20V.
  • One participant shares a video resource that may aid in understanding the circuit, although they note the presentation is rushed and may require multiple viewings.
  • A later reply acknowledges the importance of the diode in determining the output voltage drop.

Areas of Agreement / Disagreement

Participants express differing views on the behavior of the circuit under the conditions described, particularly regarding the role of the resistor and the implications of the time constant. The discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Participants highlight the dependence of the time constant on both resistance and capacitance, indicating a need for clarity on how each component influences circuit behavior.

Abdulwahab Hajar
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Hello everyone, I hope you could help me with the analysis of this circuit.
the output voltage is supposed to be similar to the input but shifted upwards by 20V, so basically it's between 0 and 40V... but why?
I mean when the input is 20V, the diode is reverse biased... and the capacitor charges... our output voltage depends on the ratio of the resistance to the capacitive reactance... at least until the capacitor fully charges... but then what happens?

Thank you
 

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Abdulwahab Hajar said:
I mean when the input is 20V, the diode is reverse biased... and the capacitor charges...

no. They told you the time constant is large, so the capacotor does NOT charge through the resistor.

Your thought tool should be this: "Time constant is large, eh? If i take that to the extreme how would the circuit behave? Limit would be infinite time constant... so what would go on if that resistor were nearly ∞ or not even there ? "

In your mind snip out that resistor and repeat your thought experiment , considering both Vt transitions.
 
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jim hardy said:
no. They told you the time constant is large, so the capacotor does NOT charge through the resistor.

Your thought tool should be this: "Time constant is large, eh? If i take that to the extreme how would the circuit behave? Limit would be infinite time constant... so what would go on if that resistor were nearly ∞ or not even there ? "

In your mind snip out that resistor and repeat your thought experiment , considering both Vt transitions.
I really can't see where this is going, a bit more insight would be highly appreciated...
I mean a very high resistance would mean almost 0 current given that the voltage supply is constant... but that doesn't really get me anywhere..
Also sir, they said that the time constant is large... how would we know if that indicates a large resistance or a large capacitance.. since the time constant is RC and dependent on both...

Thank you!
 
Abdulwahab Hajar said:
I really can't see where this is going, a bit more insight would be highly appreciated...
I mean a very high resistance would mean almost 0 current

What about the diode ?
 
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Abdulwahab Hajar said:
the voltage supply is constant
??
upload_2018-3-10_15-31-31.png

looks to me like voltage goes from +20 to -20 then back to +20, maybe repeating that forever they didn't say .

You are not operating the circuit in your mind.
 

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jim hardy said:
What about the diode ?
Got it sir, I forgot that the diode would determine the voltage drop Vo...
Thank you!
 
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