Voltage tester, tick-tracer, glow-tip, non-contact voltage tester... whatever. Same thing. I call it a voltage sniffer, but the technical name for this device is a capacitive voltage sensor. That's a ...

Relays are electromechanical devices that use a magnetic solenoid to actual a switch. When current is passed through the solenoid coil, it produces a magnetic field. The magnetic field is strengthened ...