Variable Capacitance Sensor

Capactive transducer or capacitive sensor or variable capacitance transducer.

Variable capacitance sensor. C εo x εr x a d. Capacitance is a function of effective area of conductor the separation between the conductors and the dielectric strength of the material. They utilize the electrical property of capacitance and the change of capacitance based on a change in the electrical field around the active face of the sensor. A capacitance sensor of two parallel plates of overlapping area of 5x10 4 m2 is immersed in water.

To tune a radio therefore it is sometimes called a tuning capacitor or tuning condenser or as a variable reactance e g. The variable capacitance diode is a product that makes use of the capacity characteristics of the depletion layer. For impedance matching in antenna tuners. The depletion layer occurs in the pn junction of the diode when the voltage is applied in the reverse direction and the thickness varies in proportion to the reverse voltage.

The stiffness and strength of the material can be chosen to provide a range of sensitivities and operating pressures. Ato sintayehu challa exercise on variable capacitance sensor 1. The capacitance c between the two plates of capacitive transducers is given by. A sensor fabricated by this principle is often used to measure the liquid level of a liquid ie a capacitive liquid level sensor and the thickness of a material.

Capacitive proximity sensors are non contact devices that can detect the presence or absence of virtually any object regardless of material. A variable capacitance sensor is constructed with its capacitance plates connected at their center. It is described in the equation below. The capacitance of the sensor is typically around 50 to 100 pf with the change being a few picofarads.

To get a large signal the sensor may need to be fairly large which can limit the frequency range of operation. In electrical engineering capacitive sensing sometimes capacitance sensing is a technology based on capacitive coupling that can detect and measure anything that is conductive or has a dielectric different from air. εo is the absolute permittivity. The conducting surfaces forming the capacitor are insulated from the central connection and each.

The capacitance c has been found to be 9 50pf. A variable medium capacitive sensor is a capacitor that is inserted between different plates of a capacitor to cause a change in capacitance. Where c is the capacitance of the capacitor or the variable capacitance transducer. A variable capacitor is a capacitor whose capacitance may be intentionally and repeatedly changed mechanically or electronically.

Capacitance of the capacitive transducers. ε dielectric constant permittivity of the dielectric medium.