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General principles of transducers (sensors)
In the strict sense of the word transducer is a device that converts a change in one quantity changes in the other. In terms of electronic transmitter ... >>>
The principles of the transformation of the measured physical parameters
In each converter, which converts the element is based on certain physical principle, which is associated with the electrical characteristics of the device so that a change in the quantity being measured   >>>
Contacts
Electromagnetic transducers
Electromotive force (E.M.F.) is generated along an explorer, when he is crossed by the variable magnetic field. And, vice versa, when an explorer moves through the magnetic field, along him generated E.M.F. (fig. 3), determined from next correlation:

E = - d(Nф)/dt,

where d(Nф)/dt is speed of change of coupling of streams .
Fig. 3. Electromagnetic transformation
Fig. 4. Inductive transformation
Fig. 5. Transformation of magnetic resistance, used in a differential transducer with an arcwise-changing output

Inductive transformation is shown on a fig. 4, where the self-induction of spool changes in accordance with the change of measurand. The change of inductance can be carried out by motion of ferromagnetic mandrel into a spool or by bringing of external changing stream in a spool with an immobile mandrel.
Transformation of magnetic resistance is shown on a fig. 5, on which chainlet of resistance between two or more changes spools (or by separate parts of one or a few spools) depending on variations of measurand. When to the system of spools an alternating current is put, then, the change of measurand is transformed in the change of output tension.