When the voltage supplying the circuit falls below the zener value, the LED lights up, and if a low current buzzer is used, it is activated. The circuit is from a 1999 American publication.
Found in old American documentation, this circuit can be implemented with modern operational...
We found this CMOS circuit in a 1978 publication. It allows you to use a standard calculator...
This configuration is used to display the characteristic curve of a diode in the virtual...