The purpose of this work is to explore the possibilities of using a capacitive sensor as a device that captures the presence of person in the room. When designing an energy-saving system, there is an important issue in choosing sensors that will monitor certain processes in a controlled room and respond to a specific algorithm.A capacitive sensor has several advantages, including high sensitivity, ease of construction and operation, low inertia, and simplicity of measurement. Such sensors can have many uses. For example, as a touchpad, a meter for measuring the amount of matter in a confined space (liquids, bulk materials, etc.), a motion detector, a presence detector, and others.This article describes the problem of using a capacitive sensor as a device for detecting human presence in the room where the sensor is installed, based on the results of the experiment. The operation of such a device is based on the sensitivity to change of capacitive couplings in the sensor sensitivity zone. When the geometric dimensions and shapes occur, the displacements and shapes change, and the sensor captures the change in capacity between its working surface and the ground. The sensor is а capacitor. Its first plate is the work surface of the sensing element, and its second plate is a ground or large object (such as a wall, a house, a lake, a car, a ship, an airplane, etc.). The dielectric is all objects in the space between these plates. The dielectric constant of such a "dielectric" depends on the objects, which are present in this space. Therefore, the sensor captures the change in the dielectric constant of the medium and, as a result, its capacity changes too. It doesn't matter if the object is moving or not - the sensor is able to fix it in the sensitivity zone.The construction of the capacitive sensor is quite simple. The sensitive element may be a wire, a metal plate, a printed conductor on the circuit board or part of the hull. Also, the number of sensitive elements can also be modified for specific purposes.The main methods for measuring capacitance include methods based on the use of dividers, bridges, changes in the lateral branch of the resonance curve, the use of automatic compensators and the use of frequency modulation circuits. The last method is chosen in the article.The measurement system in this work is a generator of electric oscillations, the frequency of which depends on the capacitance of the sensor. You can measure the results by counting the number of pulses per unit time. Such a function has, for example, a frequency meter.This article describes the features, the main parameters, problems and methods of using such a sensor based on the results of the experiment.
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