Optimizing Switching Frequency for Voltage Output in a Two-System Circuit

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Discussion Overview

The discussion revolves around optimizing the switching frequency for voltage output in a two-system circuit, focusing on the input and output impedances of the systems and the implications for capacitor charging and discharging equations. The context is primarily homework-related, involving technical reasoning and problem-solving.

Discussion Character

  • Homework-related, Technical explanation, Mathematical reasoning

Main Points Raised

  • One participant presents a problem statement and their suggested solution, seeking validation of their approach.
  • Another participant questions the determination of the time constant (##\tau##), suggesting it may involve additional resistances beyond the initially considered output impedance.
  • A third participant recommends finding the Thevenin equivalent seen by the capacitor, emphasizing the importance of including load-side resistors in the analysis.
  • A later reply acknowledges the oversight regarding load-side resistors, indicating a need for careful consideration in the calculations.

Areas of Agreement / Disagreement

Participants express differing views on the calculation of the time constant and the components that should be included in the analysis. The discussion remains unresolved regarding the correct approach to determining ##\tau## and the implications for the circuit's performance.

Contextual Notes

Participants highlight potential limitations in the initial assumptions regarding resistances and the need for a more comprehensive analysis of the circuit components. There are unresolved mathematical steps related to the Thevenin equivalent and its impact on the capacitor's behavior.

Ronaldo95163
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Homework Statement


Problem and Diagram stated below
System 2 Input Impedance: 1k ohms
System 1 Output Impedance: 100 ohms
High interpreted as Voltage greater than 2V
Low Interpreted as Voltage less than 0.5V

switchingfreq.png


Homework Equations


Capacitor Charging eqn:
V=Vo(1-e^-t/RC)

Capacitor Discharging eqn:
V=Voe^-t/RC

f=1/T

The Attempt at a Solution


Posted Below

Scan0009.jpg


Scan0010.jpg

Hey guys. This was a problem given to us on one of our assignments and that was my suggested solution...was wondering if what I did was correct.

Thanks in advance :D
 

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Last edited:
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Long story ! Some comments:

First thing that comes to mind for me is the ##\tau## : you sure it's from the 100 Ω only and not the 110 Ω ? (test: let Rin = 1M Ω !)

Second: no need for the ##\approx.## sign. Everything is given 'exactly'. Idem for increasing the 2 * 11/10 to 2.3 and decreasing the 0.5 * 11/10

--
 
As BvU points out, you need to take a closer look at how you determine ##\tau##. Suggestion: find the Thevenin equivalent that the capacitor sees. Note that this will include the load-side resistors too!
 
Good thing gn is on the lookout ! I had forgotten those load side guys. Rustiness...
 

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