Switching circuit diagram This type of circuit use inverter switch signal or many think use this circuit signal 0 up transistor on and another circuit off 1 down transistor on and up off.This circuit is very use full supply 12Volt . At that time, Motors are invented and scientists found that if we decrease the frequency of the electric supply, the eddy-current loss and hysteresis loss will gradually decrease. Therefore, the scientists decided to use 50 Hz instead of 60 Hz to reduce those losses. BC547 is an NPN Bipolar junction transistor. It is commonly used to amplify current. A small current at its base controls a larger current at collector & emitter terminals. BC557 is a widely used PNP bipolar junction transistor manufactured in small TO-92 package. It is a general purpose PNP transistor that can be used as a switch or amplifier in electronic circuits. ... The max collector dissipation is 500 milliwatt which is also an another good point to use it i