# Potentiometer question



## evmetro (Apr 9, 2012)

I want to clarify which wires are which for my various chinese pot boxes. When I put my meter between the wiper and one of the other two wires, one starts at 0 and counts up to 5k as I apply throttle, and the other one starts at 5k and counts down as I apply throttle. Which is the pot high and which is the pot low?


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## dedlast (Aug 17, 2013)

The end that starts at 0 ohms should be your ground side or low side. The other end will be the supply side or high side. That way, the wiper starts at 0 volts(-ish) since it is sitting at ground potential and then approaches 5 volts as it is moved.


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## evmetro (Apr 9, 2012)

dedlast said:


> The end that starts at 0 ohms should be your ground side or low side. The other end will be the supply side or high side. That way, the wiper starts at 0 volts(-ish) since it is sitting at ground potential and then approaches 5 volts as it is moved.


 I understand how a potentiometer works, and the resistance will be lower on the side that the wiper is closer to. Normally I just see references to one end of the resistor or the other, but when looking at a pot box wiring diagram it is common to see this:


White = Low
Black = Wiper
Red = High


On controller wiring diagrams, the wires are labeled pot high, wiper, and pot low as well. I want to be able to put my meter on a pot box and be able to rapidly determine which wires are pot high, pot low, and wiper, as they apply to the pot box application. On a pot box, it is not even possible to see the wires are soldered to the potentiometer, so a meter is the only way to identify what each wire is what, especially with chinese pot boxes that come with random color wires and no wire color description. It is easy to probe the wires until I find two that read 5k and don't change in value as the throttle rod is cycled, and those two are the resistor. The third one is the wiper. When you put the meter across the wiper and one end of the resistor, it reads 0, but goes up to 5k as the throttle is cycled. Put the meter on the other end of the resistor, and it starts at 5k at rest, and counts down to 0 as you cycle the throttle. It sounds like the wire (end of resistor)that reads 0 at rest and counts up to 5k as the throttle is cycled is called pot low, and the one that starts high and goes low is the pot high.


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## dedlast (Aug 17, 2013)

evmetro said:


> I understand how a potentiometer works...


Right, sorry about that. 



> It sounds like the wire (end of resistor)that reads 0 at rest and counts up to 5k as the throttle is cycled is called pot low, and the one that starts high and goes low is the pot high.


Logic would say that this is the way it works but, given the source, logic may not apply.


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## Tesseract (Sep 27, 2008)

evmetro said:


> Normally I just see references to one end of the resistor or the other, but when looking at a pot box wiring diagram it is common to see this:
> 
> 
> White = Low
> ...


That color scheme does not conform to accepted practices in electronics for a potentiometer; white should be the wiper and black should be low.


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## evmetro (Apr 9, 2012)

Tesseract said:


> That color scheme does not conform to accepted practices in electronics for a potentiometer; white should be the wiper and black should be low.


Exactly! There are many different colors that come on pot boxes, so the wire color should not be trusted. What the wiring diagrams specify is high, low, and wiper, but our multi meters don't read "pot high" or "pot low".


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