Ferromagnetic Variometer

Ferromagnetic VariometerFerromagnetic variometers (variometers with ferromagnetic cores) are used as adjusting components in oscillating circuits, for example, in car receivers. A ferromagnetic variometer consists of a cylindrical or rectangular coil, inside of which a core of a material with high magnetic permeability (such as ferrite, for example) is inserted. The higher permeability of the core material is and the closer it is to the coil winding, the greater is the overlap ratio of the ferromagnetic variometer. If we use a ferrite core, we can obtain the overlap factor of 25...30 or more. It is advisable to select cores, which have 5...10 times greater length than the diameter, and the core diameter less than the outer diameter of the coil by 0.5...1 mm. There is an opinion that overlap ratio of ferromagnetic variometers is very low, and is just a little bit higher than 2. However, if we use (as in our case) a 2000 nm ferrite, we'll obtain the overlap ratio of 6 or even higher.Ferromagnetic variometers may be used to adjust several oscillating circuits at a time. In this case, the alignment of configurations of the receiver preselector circuit and the heterodyne is usually achieved by connecting additional mating inductance coils. Therefore, ferromagnetic variometers of the preselector and the heterodyne are identical. The alignment can also be achieved by using cores of different shapes and sizes, or coils with different arrangement of winds. In general, in many cases adjustment of radio-frequency equipment can be performed with the help of ferromagnetic variometers, and in many cases they are more convenient than the modern varicaps.

Category:

Science & Technology

Tags:

• coil
• contour
• core
• electronic components
• ferrite
• receiver