Design and construction of a 220v voltage stabilizer with off delay timer

Abstract

Power line fluctuations and cut-offs in electrical installations causes damages to electrical appliances connected to the line. It is may be more fatal in the case of domestic appliances such as fridge and other sophisticated appliances like TV sets, DVD players, computers etc. If a fridge is operated on low voltage, excessive current flows through the motor, which heats up, and get damaged. It can be used to protect the whole installation from undesirable over and under line voltages, as well as surges caused due to sudden failure/resumption from the supply authority. Here is a low cost voltage stabilizer, which is fabricated using transistors and other discrete components. When the circuit is installed in the main electrical supply it will help in regulating the rate at which the surge voltages occurs. The 220v voltage stabilizer with OFF delay timer presented here is an in expensive and reliable circuit for protecting such equipment’s from damages. Whenever the power line is switched on it gets connected to the after conditioning it within a nominal voltage level. If there is high or low fluctuations beyond the sets limits the circuit is able to deduct or add some level of voltage to ensure safety of the appliance. This circuit has been designed, built and evaluated by me to use as a protector for sensitive appliances connected to the supply. This is designed around readily available semi-conductor devices such as standard bipolar medium power NPN transistor and timer IC. Its salient feature is that no relay hunting is employed.