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 makes use of a transconductance operational amplifier. It generates signals with TTL...
This circuit uses na Unijunction Transistor (UJT) to produce a modulation tone for several...
This circuit was found in General Electric documentation from the 1980s. The circuit uses couplers...