The complete circuit diagram for the
Digital I.C. Tester is shown in Fig.1. When
power is supplied to the board, it first pass-
es through bridge rectifier REC1. If the
input supply input is a.c., REC1 converts it
to d.c. If the input is already d.c. it ensures
that the polarity is correct for IC1, which
then regulates the voltage down to approx-
imately 5V. Capacitors C1 to C4 plus C11
provide smoothing.