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 circuit, found in a 1964 US documentation, consists of a selective amplifier that lets only...
We found this circuit in an old documentation from the 70s. Its purpose is to indicate the...
We found this circuit in the April 1996 issue of Electronics Now magazine. The circuit uses a...