The operational amplifier is the basis of many signal processing
elements, the basic amplifier being supplied as an integrated circuit on a
silicon chip. It has two inputs, termed the inverting input (-) and the
non-inverting input (+) and is a high gain d.c. amplifier, the gain
typically being of the order of 100 000 or more. Figure 1.42 shows the
pin connections for a 741 operational amplifier with the symbol for the
operational amplifier. Pins 4 and 7 are for the connections to the supply
voltage for the amplifier, pin 2 for the inverting input, pin 3 for the
non-inverting input. The output is taken from pin 6. Pins 1 and 5 are for
the offset null. These are to enable circuits to be connected to enable
corrections to be made for the non-ideal behaviour of the amplifier.