Potentiometer is a kind of variable resistor. It is usually composed of a resistor body and a rotating or sliding system, that is, a movable contact moves on the resistor body to obtain part of the voltage output. The main function of the potentiometer is to adjust the voltage (including DC voltage and signal voltage), divide the voltage, varistor and control current. There are generally 5 types of potentiometer materials: alloy type (wirewound potentiometer (WX) and block metal film potentiometer), synthetic type (solid potentiometer (WS), synthetic carbon film potentiometer (WH), synthetic glass glaze Potentiometer (WI), conductive plastic potentiometer), film type (metal film potentiometer (WJ) metal oxide film potentiometer (WY), carbon film potentiometer (WT)), photoelectric type (resistive photoelectric potentiometer, junction Type photoelectric potentiometer), magnetic sensitive type (magnetic sensitive potentiometer, magnetic sensitive diode potentiometer) electronic components generally we commonly use potentiometers: wirewound potentiometers, synthetic carbon film potentiometers, organic solid core potentiometers, metallic glass Glaze potentiometer, conductive plastic potentiometer, digital potentiometer.
The wirewound potentiometer is made by using constantan wire or nickel-chromium alloy wire as a resistor and winding it on an insulating frame. Advantages: small contact resistance, high precision, and small temperature coefficient. Disadvantages: poor resolution, low resistance, poor high-frequency characteristics.
The synthetic carbon film potentiometer is made by coating the surface of the substrate with materials such as carbon black, graphite, and quartz that have been ground. Because of the simple process, it is the most widely used potentiometer. Advantages: high resolution, strong wear resistance and long service life. Disadvantages: the noise generated by the current is large, the nonlinearity is large, the moisture resistance and the resistance stability are poor.
The organic solid core potentiometer is a method of heating and plastic pressing to press the organic resistance powder into the groove of the insulator. Compared with the carbon film potentiometer, it has the advantages of good heat resistance, high power, high reliability, and good wear resistance. Disadvantages: large temperature coefficient, greater dynamic noise, poor moisture resistance, more complicated production process, and relatively poor resistance accuracy.
The metal glass glaze potentiometer is made by mixing metal silver, palladium, rhodium, ruthenium and other oxides and glass glaze binders into a slurry, and then using screen printing to print the glass glaze slurry on the ceramic substrate, and then at high temperature Sintered under conditions. Due to the thick film of the resistor body, this type of potentiometer is also called a thick film potentiometer. Advantages: good heat resistance, wide resistance range, good moisture resistance, large contact resistance, good wear resistance, and long service life. Disadvantages: The current produces high noise and is not suitable for input circuits with high gain and low noise.
Conductive plastic potentiometer is a special process DAP (diallyl phthalate) resistor paste is coated on the insulator, heated and polymerized into a resistive film, and the DAP resistor powder is thermoplastically pressed into the groove of the insulating substrate to form a solid core As a resistor. Advantages: good smoothness, excellent resolution, good wear resistance, long life, low dynamic noise, and high reliability. Disadvantages: The contact resistance is slightly larger, and the use has an ambient temperature range.
Advantages of digital potentiometers: flexible use, high adjustment accuracy, non-contact, low noise, not easy to foul, anti-vibration, anti-interference, small size, long life, etc. It can replace mechanical potentiometers in many fields. Disadvantages: Due to the limitation of CMOS technology, the passband is relatively narrow.