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The opamp was
originally designed to
carry out mathematical
operations in analogue
computers, such as
bombsights, but was soon
recognised as having
many other applications.
The opamp usually comes
in the form of an 8 pin
integrated circuit, the
most common one being
the type 741.
It has two inputs and
one output.
The input marked with a
- sign produces an
amplified inverted
output.
The input marked with a
+ sign produces an
amplified but non
inverted output.
The opamp requires
positive and negative
power supplies, together
with a common ground.
Some circuits can be
designed to work from a
single supply.
If the two inputs are
joined together, then
the output voltage
should be midway between
the two supply rails,
i.e. zero volts.
If it is not, then there
are two connections for
adding a potentiometer,
to remove this OFFSET.
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