This compact mains voltage sensor is intended to monitor and signal to another circuit, for instance a microcontroller, about the presence and/or absence of the ac mains voltage. For this task, a ...

Okay, I'm building a serial link cable for my TI calculator and the plans call for two zener diodes. What exactly is a zener diode? Is that just a regular diode, because I have some diodes, and if ...

However, the circuit described here performs a simple go/no-go test on these diodes while limiting forward current and reverse voltage to safe levels (see the figure).