Using the 555 and 7400 this circuit was found in the September 1977 Radio Electronics magazine. The power supply must be made with a voltage of 5 V.
This small audio amplifier was found in the May 1994 issue of Electronics Now magazine. The power...
The displayed relay operates with an audio signal applied to the input. The transistors can be...
The circuit shown in the figure and uses the diode in the leakage current operation mode. In it,...