Many magnetic transducers can be found in electronic applications functioning as sensors. Basically they are formed by a coil that can be used to pick up any change in the magnetic field produced by a magnet under certain conditions, or a coil that produces a magnetic field from a current.
Loudspeakers and headphones are magnetic transducers, as explained in other articles, but are treated as a separate item because of their importance in electronics. Microphones and diskettes that read heads and position sensors are other examples of magnetic transducers used as sensors. The writing heads of a Winchester disk or disk drive are magnetic transducers operating in the inverse mode.
Symbols and Types
The symbols and types of some magnetic transducers are shown in Figure 1.
Specifications
Depending on the application, the transducer can show specifications as current, voltage, type of signal, or a part number. The most common is a part number specification.
Where they are found
Pickup coils, sensors, microphones, Winchester disk, and disk drives are all examples of magnetic sensors.
Testing
A multimeter can be used to test the continuity of the coil. Magnetic transducers in general must present resistances ranging from less than 1 ohm to more than 1000 Ω based on the application. This test doesn't reveal other problems such as shorts or mechanical failures.
