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 synthesizes a sinusoidal signal from logic pulses that can be obtained from an...
This oscillator can be found in other articles on the site. This is from a 4 MHz documentation, remembering...
This circuit has its battery charged by a solar system. The circuit uses components that admit...