This receiver was found in a 1924 book by Gernsback. The circuit uses three tubes and is powered by 3 batteries of different voltages, common at the time.
This modulator circuit for AM transmitters was found in a 1960 Sylvania transistor manual. Modern...
circuit is used to increase the sensivity of a relay. A 50 to 100 mA relay can be triggered with...
We find this circuit in an Electronics Now. The indication of the logic level is done on a...