DESIGNING OF FINAL CIRCUIT
Hence the complete power system is as follow:
Next we need to learn how to decide specifications of TRANSFORMER.
Voltage specification of the transformer is decided according to the requirements of the system for power supply. If we require V volts at the output for the system, then how would be decide the specification of the transformer.
 We have a voltage drop of 12 Volts in the bridge rectifier.
 Also input voltage at the voltage regulator should be 23 volts higher than the output required.
As we require V volts at the output, hence at the input of the voltage regulator, minimum voltage should be V+3 volts. There would also be voltage drop of around 2 volts in the diodes of bridge rectifier, hence we need to have voltage level of (V+3) + 2 volts at the input of bridge rectifier. So transformer must supply the peak voltage of V+5 volts but specification of the transformer we specify the rms voltage not the peak voltage.
So the voltage specification of the transformer required, with DC voltage requirement as V is (V+5) / Volts (transformer with no center node)
(V+5) / Volts (transformer with center node)
Q if we need the DC voltage of 6 volts at the output.
Ans: Then the specification of the voltage we require is (6+5) / = 7.8 V. Hence we are using a transformer with no center node which provides output voltage of more than 8 volts or the voltage of more than 4V & + 4V.
Current specification: The current specification of the transformer is decided according to the current requirement of the system. If we require current of I miliamperes for the system, then the current rating of the transformer should be greater than I miliamperes.
