Potentiometer is a typical contact type absolute angle sensor.
What is Potentiometer
Potentiometer is a typical contact type absolute angle sensor. It has a sliding contact on the resistance film (including carbon resistance film, conductive plastic film, metal resistance film, conductive ceramic film, etc.). By external action, the position of the contact point is changed so as to change the ratio of the upper and lower resistance of the resistance film, and the output voltage changes with the external position. Potentiometer is composed of electronic components and cursors. Cursors can slide on the surface of components, including linear sliding type and rotary type. The former is used to detect linear displacement, the latter is used to detect angle, tilt angle, etc. Obviously, pressure, weight, flow, etc. can be changed into mechanical displacement first, and then converted into electrical signal through potentiometer.
Potentiometer Pinout &Configuration
Potentiometer has threeterminals, as shown in the table.
|Pin No.||Pin Name||Description|
|1||Fixed End||This end is connected to one end of the resistive track|
|2||Variable End||This end is connected to the wiper, to provide variable voltage|
|3||Fixed End||This end is connected to another end of the resistive track|
- Type: Rotary a.k.a Radio POT
- Available in different resistance values like 500Ω, 1K, 2K, 5K, 10K, 22K, 47K, 50K, 100K, 220K, 470K, 500K, 1 M.
- Power Rating: 0.3W
- Maximum Input Voltage: 200Vdc
- Rotational Life: 2000K cycles
How does a potentiometer work?
As far as we know, resistors should always have two terminals, but why a potentiometer has three terminals, and how to use these terminals. It’s easy to understand the purpose of these terminals by looking at the chart below.
The figure shows the parts inside the potentiometer. We have a resistance track whose complete resistance will be equal to the rated resistance of the pot. As the symbol shows, a potentiometer is nothing more than a variable resistor at one end. Suppose a 10k potentiometer, if we measure the resistance between terminal 1 and terminal 3, we will get a 10k value, because both terminals are fixed ends of the potentiometer. Now, as shown in the figure above, let’s put the wiper 25% away from terminal 1. If we measure the resistance between terminal 1 and terminal 2, we will get 25% of 10km, i.e. 2.5km. If we measure the resistance between terminal 2 and terminal 3, we will get 7.5km.
Therefore, terminals 1 and 2 or 2 and 3 can be used to obtain variable resistance, or knobs can be used to change the resistance and set the required value.
- Voltage and Current Control Circuits
- Used as volume control knobs in radios
- Tuning or controlling circuits
- Analog input control knobs
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