Constructing and testing an electronic circuit with first order low pass filter

Thread Starter

gaffer

Joined Aug 28, 2009
1
Hi, was just wondering if anyone could help.
This is a university project i have been given. Im very unexperienced in this area of electronics so i am really struggling, especially with the measurements and calculations side of the experiment. Here is the basics of the assessment.

You are required to produce a report detailing how you would construct and test an electronic circuit.

You need to detail a circuit comprising of a resistor of 1 KΩ and a capacitor to produce:
(i) a first-order low pass filter with a cut off frequency of 2.5KHz
(ii) a first order high pass filter with a cut off frequency of 4KHz
You are required to produced a circuit diagram for each case, and calculate the value of the capacitor required to meet the frequency response requirements stated.

This may seem like an easy task, but as i said i have absolutely no experience with this and find it difficult to state the measurements and calculations needed due to the fact i am not actually taking part in the experiment, only writing a report about it.

If anyone could help or point me in the right direction i will be very grateful,
thanks for your time
 

Audioguru

Joined Dec 20, 2007
11,251
A first-order filter is extremely simple because it has only two parts.
The frequency calculation is also extremely simple.

Why are you writing a report about an electronics circuit that you know nothing about?
Can't you ask your teacher to explain it?
 

t06afre

Joined May 11, 2009
5,936
In this case I would say your Goggle tool is as god as mine. But I am in a good mood so I can give you some hints. Then doing this kind of circuits analysis we as a thumb rule plot the function Voutput/Vinput as a function of frequency. The X-axis is the frequency. Use Log10 based scale. Also your teacher is there to help you. But Teachers hate questions like "please help I do not understand anything" Before you ask your teacher for help you should compile a list explaining what you have done so far and why you struggle, with references to your text books. Often by doing this the problem will solve itself
 

rogs

Joined Aug 28, 2009
279
As you are only writing a report on how to do this, rather than showing your understanding of the mathematical details of actual filter design, why not use a 'real world' solution, and let others worry about the academics?

This: http://focus.ti.com/docs/toolsw/folders/print/filterpro.html is a free application that will simply let you enter the parameters you need, and give you the results for the components you require.
Can't see the point of getting involved in detailed filter maths, if you don't have to, when someone's already done it for you, and made it available for free! :)

Typical results for your specific filters
:

 
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