If you have the skills and can get your hands on SMD components, you can assemble this small amplifier. We found it in the Radio Electronics Experimenter special edition from 1990.
This circuit was obtained in documentation on medical applications from 1966. The circuit is used in...
This circuit, which appears from other sources on this site, converts a voltage into a current....
This interesting circuit makes the needle of a microammeter oscillate at random, imitating a...