
There are three types of Variable Resistors, each of which consist
of a three terminal resistor; two fixed end leads and one lead attached
to a variable tap. The variable tap is movable to change the resistance,
between the tap and terminal.
Potentiometer: Designed for frequent changes ~ a volume
control
Trimmer: Designed for less then frequent changes [occasional]~ a
trim pot on a PCB to finalize a circuit resistance.
Rheostat: A three terminal potentiometer which only uses two
terminals.
The material used determines the Variable Resistor's operational range
[temperature and wattage]. The material may be;
Carbon composition, Resistive wire [Wirewound],
Conductive Plastic, and Cermet [a mixture of ceramic and
metal].
| Potentiometer Types | Carbon Composition | Cermet | Conductive Plastic | Wirewound |
| Humidity | Sealed | Immune | Large Change | ---- |
| Temperature | Sealed | Very Good | Large Change | ---- |
| Wattage | Medium | Low/High | Low | Medium/High |
| Resistance Range | High | High | High | Low |
| Resistance Value | 50ohm - 50Mohm | 10ohm - 5Mohm | 100ohm - 5Mohm | 10ohm - 100Kohm |
| Frequency Range | ---- | High | ---- | Very Low |
| Tolerance | ---- | ---- | ---- | ---- |

Back to the Logic Design Page or the [Variable Resistors],
Potentiometer Manufacturers
Page.
Select the Components icon below for all other Passive or Active
components.
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