Other settings like this can be found on this website. This makes use of old operational amplifiers, as the publication where we obtained, but equivalents can be used.
This circuit was found in Philips documentation from 1967. The phototransistor is from that time,...
We found this third-order Butterworth asymmetric filter in an old manufacturer documentation. The...
We found this circuit in a publication for radio amateurs of 1976. The operational amplifier is a...