active filters

Thread Starter

mehtab102

Joined Jun 21, 2011
62
i want to make active filters
1.low pass filter
2.high pass
3. band pass
4.band stop

plz help me with circuit diagram and with ic's
 

SgtWookie

Joined Jul 17, 2007
22,230
Here is a very helpful design reference guide:
http://www.ti.com/lit/an/slod006b/slod006b.pdf
"Opamps for Everyone"
Active filter design techniques are covered in Chapter 16; there are 63 pages to read.

You need to work out the calculations yourself, and show your work, or your instructor will likely give you a low grade.

You can check your work by using this online filter design calculator:
http://www.ti.com/tool/filter-designer
 

Thread Starter

mehtab102

Joined Jun 21, 2011
62
A.A,
i want to shear that this account is not using by single person.all my class fellows using this site by my account...so sory to all...acctually the person who shear this last post who wants to know that in active filters how to find the the cap, and resister value for all low pass ,high pass band pass and band stop...
this was the question...but he didnt explor his question.he told me to find out.then i open ths site and read ur comments..once again sorry to all.plz help him.
thnx!
 

SgtWookie

Joined Jul 17, 2007
22,230
A.A,
i want to shear that this account is not using by single person.all my class fellows using this site by my account...so sory to all...acctually the person who shear this last post who wants to know that in active filters how to find the the cap, and resister value for all low pass ,high pass band pass and band stop...
this was the question...but he didnt explor his question.he told me to find out.then i open ths site and read ur comments..once again sorry to all.plz help him.
thnx!
Accounts are not supposed to be used by multiple people.

Each person should have their own account. It is not that difficult to register for one. Having multiple people on the account makes things very confusing.
 

SgtWookie

Joined Jul 17, 2007
22,230
sorry sgtwookie
is their any solution for his q??
and he told the cut of freq. is 80khz.
waiting for ur response
Certainly there is a solution - but you won't get there with a 741 opamp; as they are far too slow for 80kHz. You would be lucky to get 10kHz out of a 741.

He will need a better opamp.
He will also need to read through the design guide that I posted a link to, and check his work using the calculator I linked to.

I'm not going to do it for him, as that would defeat the entire purpose of him learning how to do it.
 

Wendy

Joined Mar 24, 2008
23,415
Folks, if you have a problem with some one please move on, no personal attacks. I have moderated a post here because it was over the top. This site will be friendly to everyone.

To the OP, the subject you working on is quite complex. Whole books have been written on the subject. I have researched the subject deeply, and do not consider myself expert on the subject.

However, a couple of things stand out.

The term you are looking for is "active filters". Your first post shows you know this, but stick with the phrase and Google it, you will get many hits. There are many, many types of filters.

Even within the description of active filters you will find many types of filters. A simple integrator/differentiator are 1st order filters. They are very simple, one op amp, two resistors, and a capacitor. It goes up from there, with many many different kinds and curves.

Pick a type, draw and post a schematic, and ask your questions. Because this subject is so complex you can dance around the subject forever and not get any answers unless you have specifics.

Wookie is right on several fronts.

Make your own account. It is not hard, so there is no excuse for sharing accounts.

The 741 is a beginners part. It is hard to destroy (but I did it several times when I was in college), it is very limited (which is good for a teaching part, you can see what the limitations of an op amp are), and it is cheap.

If you MUST use a 741 then use very low frequencies to play with. Stick with under 5Khz. Otherwise find an op amp that can go much higher frequencies for practical active filter applications.
 
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