This circuit was found in a publication by Edelman from 1924. The power comes from the battery and the listening is through a high-impedance headphone.
This shield circuit allows recording of the signal from a serial output on a cassette recorder, with...
This Japanese radio receiver is from the 60s. It has 6 transistors and is powered by 4 batteries with...
The integrated circuit used is a voltage reference from Motorola. This configuration was obtained in...