Author Topic: Highpass  (Read 172 times)

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Offline Mepakos

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Highpass
« on: September 20, 2019, 08:05:38 am »
Hi all. If the resistance increases, what changes in the picture on the output signal?
 

Offline hamster_nz

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Re: Highpass
« Reply #1 on: September 20, 2019, 08:08:35 am »
As a thought experiment, increase the resistance to infinity. What do you expect to see?

Or what would you expect to see if you decreased it to zero?

(No direct answers are ever given to homework!)
Gaze not into the abyss, lest you become recognized as an abyss domain expert, and they expect you keep gazing into the damn thing.
 

Offline Mepakos

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Re: Highpass
« Reply #2 on: September 20, 2019, 08:56:51 am »
Same result i think. Electricity would flow because the resistance doesnt matter?
 

Offline radiolistener

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Re: Highpass
« Reply #3 on: September 20, 2019, 10:23:40 am »
Here is Ohm's law:

U = I * R

Your circuit is a passive high pass filter. RC cut-off frequency is:

f = 1 / (2 * pi * R * C)

This is pretty easy to understand what happens if you change R.
« Last Edit: September 20, 2019, 11:30:38 am by radiolistener »
 

Offline Zero999

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Re: Highpass
« Reply #4 on: September 20, 2019, 03:50:07 pm »
Same result i think. Electricity would flow because the resistance doesnt matter?

Nope, because the ratio of resistance to capacitance determines the upper cut-off frequency, which affects the step response.

How about simulating the circuit?

Try  simulating it. Start with a 10Hz squarewave, a 100nF capacitor and a 22k resistor.
https://www.falstad.com/circuit/
 
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