المقياس ذو الملف المتحرك - المجهار ذو الملف المتحرك - اهمية المغنطيسية ..الإلكترونيات

Moving coil meter - Moving coil microscope - Gate circuit "or" - Importance of magnetism .. Electronics

Moving coil meter

The moving coil measuring device consists of a permanent magnet that creates a strong magnetic field in the space between its two round poles. A closed coil is placed in it, i.e. in its air gap, which is free to move and rotate. The movement of this coil is controlled by two thin wire springs fixed on the axis of the coil to which the measuring indicator is connected. The passage of current in the coil creates a magnetic field whose lines intertwine with the lines of the permanent magnet field. This leads to the presence of repulsive forces that rotate the coil and the indicator attached to it. The angle of rotation of the coil depends on the intensity of the current passing through it. The greater the intensity of the current, the greater the deviation of the indicator. In this way, the intensity of the current, voltage, or any other electrical quantity can be measured. When the current stops flowing, the coil returns to its original position.

61 - Changing the magnetic field leads to the generation of a V.D.K.
62 - Moving coil measuring device.

Moving coil microscope

The moving coil microscope consists of a conical membrane carrying a very light coil through which current passes by flexible connections (63). This coil is located in the narrow air gap of the magnetic assembly and can move easily in and out of the gap and on the same axis as the conical membrane.

The audio signals passing through the coil generate a magnetic field that changes according to the change in sound intensity. The interaction between this field and the fixed field of the permanent magnet causes both the coil and the conical membrane to vibrate in and out. This movement pushes and disturbs the air, creating sound waves similar to the sound to be heard.

63 - Moving coil loudspeaker

The coil is called the "speech coil" and we can differentiate between dynamic loudspeakers and electrodynamic loudspeakers in that the former contain a permanent magnet while the latter contain electromagnets surrounding the middle leg of the group and a current passes through them that generates the desired magnetic field.

As for moving coil loudspeakers, the vibration of the membrane leads to moving the coil in and out of the air gap of the magnetic field, generating an electromotive force in it.

The "OR" gate circuit

Small iron cores are used in computers to achieve purposes. Figure (64) shows one of these elements and it has three coils, two of them for the input and the third for the output. This circuit is characterized by the fact that it gives an output only when there is a certain voltage on its input A or on its input B.

64 - The magnetic "OR" gate used in the computer.