This circuit visually indicates that a high voltage is present in an outlet or other point. The neon lamp is common, and the appearance of the assembly is suggested in the same figure.
The figure shows how to implement an alarm buzzer in an LM3914 to warn about crossing the scale...
This circuit can act as a shield being controlled by a microcontroller by pin 1 or 2. The...
This circuit was obtained from a 1980's QST magazine. The circuit can generate 1 to 15 MHz signals...