Built from a P-N junction, this device presents very low resistance to current flowing in the forward direction and extremely high resistance in the reverse direction. It requires a small forward voltage drop, typically around 0.7 volts for silicon, before it begins conducting. They are fundamental building blocks used for rectifying AC power, protecting circuits from reverse polarity, and demodulating signals.
Put a flyback diode across the relay coil so the voltage spike doesn't blow out the driving transistor.
Related terms
Zener diode
A specialized diode designed to allow current to flow backwards when a specific reverse voltage is reached.
Rectify
To convert alternating current into direct current using components that only allow one-way electron flow.
Junction
The physical interface where two different materials or conductors meet.
MOSFET
A metal-oxide-semiconductor field-effect transistor is a voltage-controlled switch used to amplify or switch electronic signals.