DAMPER DIODES

A damper diode is a diode that detects a high voltage and SQUELCHES IT (reduces it -
removes it). The signal that it squelches is a voltage that is in the opposite direction to
the "supply voltage" and is produced by the collapsing of a magnetic field. Whenever a
magnetic filed collapses, it produces a voltage in the winding that is opposite to the
supply voltage and can be much higher. This is the principle of a flyback circuit or EHT
circuit. The high voltage comes from the transformer.
The diode is placed so that the signal passes through it and less than 0.5v appears
across it.
A damper diode can be placed across the coil of a relay, incorporated into a transistor
or FET or placed across a winding of a flyback transformer to protect the driving
transistor or FET.
It can also be called a "Reverse-Voltage Protection Diode," "Spike Suppression Diode,"
or "Voltage Clamp Diode."
The main characteristic of a Damper Diode is HIGH SPEED so it can detect the spike
and absorb the energy.
It does not have to be a high-voltage diode as the high voltage in the circuit is being
absorbed by the diode.