Version 1.0, August 31, 2001, Copyright, Hugh Jack 1993-2001

13.3.1 Potentiometers

 

· A variable resistor is used to convert an angle or displacement to resistance/voltage.

 

· These give absolute position readings.

 

· Linear resistors are used for measuring linear displacement.

 

· The basic principle of operation is that a moving wiper (sensor input) moves a contact along a resistor. The ends of the resistor are connected to reference voltages. As the wiper moves the potentiometer acts as a voltage divider and produces a voltage proportional to position.

 

 

· rotational potentiometers are the most popular. These may be limited to a fixed range either less than 360, or some number of turns.

 

 

· Advantages include,

  1. - typically inexpensive
  2. - easy to use
  3. - very common in a variety of forms, resistances, etc.

 

· Disadvantages include,

  1. - limited accuracy (there are high cost solutions)
  2. - subject to mechanical wear