Build a filter that will accept a 200hz square wave

[zekester]

i need to build a filter that will accept a 200hz square wave that will remove all harmonics other than the fundamental. there also needs to be an option to pass or block the dc value in the circuit. i understand the how to make the filter, but not the part about how i would have an option with the dc. how would i do this?

 

[Jeff273]

Add another LP filter as shown. You did not specify a response time, so you'll have to calculate the R and C. A sufficiently low-pass filter will pass the DC component with some ripple that you must define as acceptable. Its a trade-off between response time and AC ripple.

https://www.physicsforums.com/attachment.php?attachmentid=3256&stc=1

 

[Jeff273]

Just reread your post. Do you want:

1) The AC component only with an option to pass the AC + DC

or

2) The AC component only with an option to eliminate the AC and pass just the DC component?