Automobile Electrical and Electronic Systems, 5th Edition

Electrical and electronic principles

51

A phase sensitive detector can be used to convert the movement into a DC

voltage, often 5 V. For a device moving 12 mm this gives a sensitivity of

0.42 V/mm.

LVDTs are used in some manifold pressure sensors where a diaphragm

transforms changes in pressure to linear movement.

1.7.10  Hot wire air ow sensor

The distinct advantage of a hot wire air ow sensor is that it measures air

mass ow. The basic principle is that, as air passes over a hot wire it tries

to cool the wire down. If a circuit is created such as to increase the current

through the wire in order to keep the temperature constant, then this current ...