I am trying to build a 3rd order low pass filter. The design that im following uses 1 TL072. Since I could only find TL071 in my area i decided to use 2 of those to replace the dual opamp. My circuit is still not behaving properly though. When I'm doing this conversion am I missing something? The TL072 has no offset pins while the TL071 has 2 for each. I just connected these offsets to ground both on both chips. Am I doing something wrong there?
This is my first time building a filter on my own after college, so I'm trying to relearn some stuff. I am thinking that the cap and res tolerances when combined might be throwing my filter off.
I am trying to build a 3rd order low pass filter. The design that im following uses 1 TL072. Since I could only find TL071 in my area i decided to use 2 of those to replace the dual opamp. My circuit is still not behaving properly though. When I'm doing this conversion am I missing something? The TL072 has no offset pins while the TL071 has 2 for each. I just connected these offsets to ground both on both chips. Am I doing something wrong there?
Thanks in advance,
I answer everything everywhere (well, the top two forums and uC forum are where I mostly hang out). What is the lowpass filter feeding? You may not need a second opamp if the Zout is not important. Just follow the 2nd order active lowpass of the first opamp with a passive RC into whatever you are feeding, depending on the Zout it may not matter.
ElectroMaster fixed the attachments quota problem.
Here is the circuit of a 3rd-order Sallen and Key Butterworth lowpass filter. The gain resistors are not needed then the opamp can be a simple follower if the RC values are different.
ElectroMaster fixed the attachments quota problem.
Here is the circuit of a 3rd-order Sallen and Key Butterworth lowpass filter. The gain resistors are not needed then the opamp can be a simple follower if the RC values are different.