Here’s
a design circuit that called over voltage protection circuit. This circuit can
called as crowbar protection circuit. This circuit is used where we need
protection against high voltage surge. The circuit has a few components, it is
very easy to build and will protect your electric equipment again over voltages.
The crowbar circuit must be mounted between power supply and the protected
device. This is the figure of the circuit diagram;
The
over voltage protection circuit is based on brute force: when the power supply
voltage increases too much a thyristor short circuit the output. This mean that
the overvoltage is quickly removed from equipment power terminals and F1 fuse
will burn. The overvoltage (crowbar) circuit is now set. Replace the wire
bridge with a fuse (5A). In repaos state the circuit take 1 mA.
