VARIABLE RESISTORS

Three types of variable resistors are used: rheostats, potentiometers, and thermistors.
1. RHEOSTAT:
used the headlamp switch to dim or brighten dash panel lighting. Rheostats have two connections, one to the fixed end of a resistor, the other one to a sliding contact on the resistor.
Turning the control moves the sliding contact away from or toward the fixed end, increasing or decreasing the resistance.
2. POTENTIOMETER:
used in airflow meter. Potentiometers have three connections, one at each end of a resistor and the third one is a sliding contact. Turning the control places more or less resistance in the circuit.
3. THERMISTOR:
NTC (negative temperature coefficient) thermistors in temperature sensors and PTC (positive temperature coefficient) thermistors in the electric assist choke.
Both types of thermistors change resistance with increasing temperature (NTC, resistance goes down as temperature goes up; PTC, resistance goes up as temperature go up.)


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