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.
The frequency of the blinking of this circuit is given by the capacitor that can have its value...
This low-current power supply was obtained in Japanese documentation from 1968. The currents are...
This simple audio booster came out in a Popular Electronics in the 90s. It serves as a booster for very...