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.
This circuit detects magnetic fields by approximation, using a Hall sensor. The components are...
The purpose of this circuit is to emit infrared pulses. However, LEDs for visible light can also...
This circuit was found in a Popular Electronics from the 1990s. The circuit indicates the level of an...