WRE-120 WRN-642 WRN-643 WRE-121 WRE-122 assembly thermocouple, varistors are usually used in circuits that need to be adjusted frequently (that is, the resistance does not need to change frequently), and play the role of adjusting voltage, adjusting current, or signal control. Its main parameters are basically the same as fixed resistors.
Type and structure of variable resistor.
The variable resistors can be divided into film-type variable resistors and wire-wound variable resistors according to the materials they are made of, and they can be divided into vertical variable resistors and horizontal variable resistors according to the structure.
The variable resistor film type variable resistor adopts a rotary adjustment method, and is generally used in a small signal circuit to adjust a bias voltage or a bias current, a signal voltage, and the like.
Membrane variable resistors are usually composed of a resistor body (synthetic carbon film), a movable contact (a movable metal reed or a carbon contact), an adjustment part, and three pins (or solder pads). Two of the fixed pins are connected to both ends of the resistor body, and the other pin (center tap) is connected to the movable contact piece. You can change the resistance between the center tap and the two fixed pins by turning the adjustment part with a small flat-blade screwdriver and changing the contact position of the movable contact with the resistor.
Membrane variable resistors are available in hermetically sealed, blue-sealed, and unsealed types.