REGULATED POWER SUPPLY
AIM: To construct a regulated power supply
Diodes (IN 4005) , IC 7805, Transformer, Capacitors, Resistors, Multimeter, etc.
(i) Block Diagram:
C2 C2 7912 7812
C = 1000 mF: C2 = 47 mF
In a typical linear power supply, AC line voltage is first down-converted to a smaller peak voltage using a transformer which is then rectified using a full wave bridge rectifier circuit. A capacitor filter is then used to smoothen the obtained sinusoidal signal. The residual periodic variation or ripple in this filtered signal is eliminated using an active regulator.
To obtain a DC power supply with both positive and negative output voltages, a center-tapped transformer is used, where a third wire is attached to the middle of the secondary winding and it is taken as the common ground point. Then voltages from the opposite ends of the winding will be positive or negative with respect to this point.
Care should be taken while connecting 78XX and 79XX ICs. Their configuration is given below:-
Output Output Input