Varistors

Varistors, also known as voltage-dependent resistors (VDRs), are a type of circuit protection device that is used to protect electronic circuits from overvoltage conditions. A varistor is a solid-state device that has a nonlinear, voltage-dependent resistance. This means that its resistance decreases as the applied voltage increases. When an overvoltage condition is detected, the varistor's resistance decreases, allowing a large current to flow and dissipate the excess voltage, thus protecting the circuit from damage. Varistors are commonly used in power supply circuits, telecommunications equipment, and other applications where protection from overvoltages is important.