Pressure is a very important parameter in most industrial
applications such as air conditioning, liquid level sensing and
flow control.
In most cases, the sensor is located close to the measured
source in a very noisy environment, far away from the receiver
(recorder, computer, automatic controller, etc.)
The transmission line can be as long as a few hundred
meters and is subject to electromagnetic noise when the
signal is transmitted as voltage. If the signal is transmitted as
a current it is easier to recover at the receiving end and is less
affected by the length of the transmission line.
The purpose of this note is to describe a simple circuit which
can achieve high performance, using standard Motorola
pressure sensors, operational amplifiers and discrete
devices.