Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
These capacitors are used as tuning capacitors in radio receivers. The two requirements of these capacitors are:
(1) Frequency stability
(2) Preventing micro phony
For frequency stability, the spacing between vanes should not change. For this the vanes are relived of all the internal stresses before assembly. To prevent micro phony, there must not be mechanical resonance over audio range of frequencies. At very high frequency (V.H.F.); vanes are either thick or widely spaced.
CONSTRUCTION: For tuning receiver and low power transmitters air dielectric capacitors are usual. A two-gang variable capacitor suitable for radio receivers contains two variable capacitors operated to a single tuning control. The various parts of a capacitor are: Frame, rotor, stator spindle and bearing. In this construction, fixed metal plates or vanes connected together form a stator and movable vanes connected together from a rotor. Capacitance is varied by rotating the shaft to make the rotor plates mesh with the stator plates. The fixed vanes are insulated from the frame work of capacitor by mounting which are made of ceramic materials. The movable vanes are spaced on the spindle by spacing washers to that they do not touch the fixed vanes at the point. Full mesh of the two sets of vanes means maximum capacitance. Moving the rotor completely out of mesh provide minimum capacitance. Losses in such air dielectric capacitors are small. The power factor at 1.5 MHz may be as low as 10-4 corresponding to a Q of 10000. Variable capacitors may be having their capacitance intestinally and rapidly change over the life of the device. They include capacitors that use a mechanical construction to change the distance between the plates, or the amount of plate surface area which overlaps, and variable capacitance diode that change their capacitance as a function of the applied reverse bias voltage. Variable capacitance is also used in sensors for physical quantities, including microphones, pressure and hygrosensors.
#questionsolved assignments..
When two objects collide like there velocities are not in the line of action of contact force then the collision is known as oblique collision. We can split also oblique collisi
construction and working of nicol prism
In a young's double slit experiment the screen is 1 meter away from the slit, the separation between the slits is 1mm and the distance between the 1st and 4th fringe is 1.2mm. Find
Action and reaction in polling forces Secure two spring balances. Make a loop in every end of a short piece of strong cord. Join a spring balance to each end and have two pupil
A helium atom is in a galaxy travelling at a speed of 4.89 x 10 6 m/s away from the Earth. An astronomer on Earth observes a frequency from the helium atom of 6.52 x 10 14 H
#question-the measurement of 30.43 degrees north of east..
Why is it that the frequency of light remains the constant as it undergoes refraction at the interface of two material mediums? Ans) If frequencies are dissimilar in different m
Give the theory of plane diffraction grating for normal incidence.
Electric charge is a physical property of matter that causes it to experience a force when near other electrically charged matter. There exist two types of electric charges, called
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +1-415-670-9521
Phone: +1-415-670-9521
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd