This primitive solar radio was found in a Gernsback publication from 1960. The transistor is made of germanium of the time and the earphone is magnetic with high impedance.
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...