Structural diagram and function of sliding resistor

    Structural diagram of sliding resistor

    Sliding resistor

    The main function of sliding resistor

    (1) Protection circuit.

    (2) By changing the resistance of the circuit part, the magnitude and direction of the current in the circuit are changed, thereby changing the voltage at both ends of the conductor (electrical appliance) connected in series. When connecting a sliding rheostat, the requirement is: "one up and one down, with the emphasis on the bottom", and the metal rod and the resistance wire each use one terminal; the actual connection should select the two terminals of the resistance wire according to the requirements.

    (3) Changing voltage. When exploring Ohm’s law, it plays the role of changing the voltage across the electrical appliances connected in series.

    (4) The resistance is measured using the volt-ampere method, based on the modified formula of Ohm’s law: R=U/I.

    Sliding resistor change law

    There are three different forms of laws of change.

    X-type is a straight line type, and its resistance value changes evenly according to the angle. It is suitable for voltage division, current regulation, etc. For example, it is used for field frequency adjustment in television sets.

    The Z type is an exponential type, and its resistance value changes exponentially according to the rotation angle (the resistance value changes slowly at the beginning and then becomes faster). It is commonly used in volume control circuits. Since the human ear's auditory characteristics for sound loudness are close to a logarithmic relationship, when the volume gradually increases from zero, the human ear is most sensitive to the volume change. When the volume reaches a certain level, the human ear's hearing gradually becomes dull. Therefore, the volume adjustment generally uses an exponential potentiometer to make the sound change sound stable and comfortable.

    D type is logarithmic, its resistance value changes according to the logarithmic relationship of the rotation angle (that is, the resistance value changes quickly at the beginning and then slowly). This method is often used for special adjustments of instruments and equipment. Using this potentiometer in a television to adjust the black and white contrast can make the contrast more appropriate.

    When making general adjustments in the circuit, use inexpensive carbon film potentiometers; when making precise adjustments, it is advisable to use multi-turn potentiometers or precision potentiometers.

    Sliding resistor

    In summary, the sliding resistor mainly plays the role of protecting the circuit by adjusting it up and down.