Electrical Gurus: Potentiometer vs VR?

[DrMaxit]

I'm having some sort of brain fart I guess you could call it while thinking about the TPS circuit. The question I'm asking myself it, whats the benefit of using a potentiometer (3 wire) over using a variable resistor (two wire)? Thinking back a few years to the few electrical classes I had, from what I remember they serve the same purpose, but, what the hell is the third wire (return wire) used for on pots? Detailed explanation please. Thanks

--Chuck

"Who's loosing his mind..."

 

[347HO]

The three legs are;
Source = power supply
Wiper = the resistive counter
Ground (not neutral) = just as it says

Normally used in a circuit where "gain" is required to fine tune a "null" or movement, whether power or resistance.

 

[DrMaxit]

The three legs are;
Source = power supply
Wiper = the resistive counter
Ground (not neutral) = just as it says

Normally used in a circuit where "gain" is required to fine tune a "null" or movement, whether power or resistance.

Thanks for the reply! I know how they both work, I just cant figure out what the ground is for on this instance. Couldn't a two wire be used (source/wiper)? Im just not sure of the ground/return...... Been a while.

Thanks
--Chuck

 

[Saleen0679]

Rheostats are typically used more for current control like a dimmer circuit. The rheostat is a single variable resistor where the wiper sweeps across the resistor to vary the current through the circuit. The wiper is connected to one of the legs.

A pot is more of a variable voltage divider circuit. Kind of like having two resistors with the wiper being in the middle and varying the resistance ratio of the two resistors. The wiper stands on its own and is used to pick off a voltage at a specific point in the circuit.