I have spent a couple hours and give up. The link below page 4 and 5 explain how to get the values for the circuit on the last page (bandpass filter, and I was leaving the .01uF in there).
**broken link removed**
The sample is freq =1K and bandwidth=100Hz. I dropped the circuit in circuitmaker and it works pretty good.
I have tried 3 times to get the values for frew=2500Hz and bandwidth=500Hz. I get R1=625, R2=32ohms, and R3=6.25K (roughy on the 3 tries).
I drop it in circuit maker and it passed 100HZ - 5Khz.. And probably more.
Does anyone have a better filter? Formula? I was using 1vp-p and was not railing the opamp at all.
Now please solve my problem, I want to design a filter that can pass the frequency 0Hz to 6Khz.. I want to use op-amp, it should be active filter... Thanks.
JimB, thank you sir. That gave me almost what I needed (thanks to both you and Ayne). Almost as it, for a single op amp filter I found the op amp will cut off the high pretty darn good. Not the lows though. So looks like I will do a highpass into the bandpass to fix that.
Ayne, try the website you sent with a TL082. It might get you want you want as it did not filter low freq well at all, but did the high very well. Now this is in CircuitMaker, not on the breadboard.
Ayne,
You hijacked this thread. You should start your own thread.
You need to pass the frequencies from 0Hz so the filter is not a bandpass filter. You need it to cut high frequencies so it needs to be a lowpass filter.
I read his link to a webpage I have been too before and it matched JimB's calcs 100%.
I guess the op amp bandpass filter really does not work well in the low freq range. Mine was 2500Hz center with width of 500Hz. According to circuit maker anyway, it rolled off at the right spot on the high but the low did not roll off down to 200Hz when I stopped looking.
I did actually build it. And now I need a high pass filter (for my lower freq) to route into the bandpass filter to fix that.
Then I guess I will need a preamp for my mic as well