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Electromechanics transducers
Electromechanics transducers are produced in different execution, but all of them are executed in form mechanical pin device, working under the action of changing physical size measuring of which is carried out. Usually contacts have a simple form and work in the discrete mode, as, for example, bimetallic switch (fig. 6)

 Bimetallic element, working as   an electromechanics transducers
                         Fig. 6. Bimetallic element, working as   an electromechanics transducers     

When the value of measurand exceeds a switchpoint, a contact comes   apart or  locked, hereupon the output signal   of transformer is formed in the reserved or broken a secret electric chain.
      Electromechanics transducers are, as a rule, digital (discrete), as their contacts can be only in two positions and are an element included/turned off.

Some other types of Electromechanical transducers 
   Electrodynamic and electrostatic transducers found the widest application in professional and consumer electro-acoustic equipment. However, some types of Electromechanical converters still also find application in various branches of engineering, e.g. communication equipment (coal, electromagnetic), as pickups and laringophone (electromagnetic, piezoelectric). So let's briefly review how they work.
   First spread a carbon Converter, which is still used as a microphone in a stationary telephones. This is an irreversible transducer-controller. When exposed to a sound pressure on the diaphragm it begins to waver. Accordingly, changing the compression force of the grains of coal powder, therefore, changes the resistance between the electrodes. Therefore, when constant electric voltage source varies the current in the circuit of the primary winding of the transformer, whose DC component appears in addition to variable.

   At the terminals of the secondary winding will be alternating voltage and shape time curve which is more or less accurately show the shape of the curve of the sound pressure p acting on the diaphragm. 
   The main advantage of carbon microphone – high sensitivity, allowing to use it without the amplifier. Disadvantages, not allowing it to be used for professional purposes: large unevenness of the frequency characteristics (narrow frequency range), significant nonlinear distortions and noise due to the rupture and restoration of contacts between the grains of coal of the piston.