I want to make this:

image-20230211101954208

First step is to find the right component values. Let's use the database again. Except...now it's probably a lot harder to find the right formula for the output voltage.

I came across TI's filter design tool and after selecting some properties this is what it came up with:

image-20230211130254275

Now it looks a bit different then the image above, but is really not. Why the first stage was added is unknown to me so I will disregard it, but the second is identical if you leave out the R1/R2 that determine the gain. Let's simulate this!

image-20230211193550689

image-20230211193620790

That looks good! On to fritzing and the breadboard. I have no 6.2k resistor so will replace with a 6.8k but the simulation looks good with it.

TL072 pinout

image-20230115105335207

In case this does not work well I can try adding 1:1 resistors on the negative input (see top image).

It works!

| Result | 10Hz | 100Hz | | ------ | ----- | ----- | | V-IN | 0.992 | 0.976 | | V-OUT | 0.888 | 0.190 |