Found in a 1924 book by Gernsback, this circuit uses a double variable capacitor, a component not very common at the time. Listening was done on a loudspeaker at the time.
February 25, 2015 - Mouser Electronics, Inc. today announced their new Robotics Technology site....
In the figure we show a simple way to use a zener diode to protect a load against overvoltage. The...
The sound produced by this circuit, from a 1978 publication, depends on the humidity between the...