# Homework Help: Switching Frequency Problem

1. Nov 23, 2015

### Ronaldo95163

1. The problem statement, all variables and given/known data
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

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

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

f=1/T

3. The attempt at a solution
Posted Below

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.

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Last edited: Nov 23, 2015
2. Nov 24, 2015

### BvU

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

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3. Nov 24, 2015

### Staff: Mentor

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!

4. Nov 24, 2015

### BvU

Good thing gn is on the lookout ! I had forgotten those load side guys. Rustiness....