This circuit was found in a 1924 Gernsback publication. The variable capacitors are dual. Listening is through a high-impedance phone.
Found in a 90s Maxim documentation, this circuit disconnects the battery in case of overload. The...
In this circuit we have the voltage multiplied by 5, obtaining between 50 and 80 V output when the...
This circuit was found in an 80's Electronic Engineering. The circuit uses operatives of the time...