potentiometer as variable resistor

justDIY

Active Member

• Dec 7, 2006

• #1

when using a pot as a variable resistor, what is the purpose of connecting the wiper to one of the resistance legs?

some schematics show the wiper tied to one leg, other show the unused leg floating.

 

Nigel Goodwin

Super Moderator

Most Helpful Member

• Dec 7, 2006

• #2

It makes no difference if everything is OK - but if the wiper should go O/C then the resistance goes O/C - except if the wiper is connected to the end, then it goes to maximum resistance.

 

justDIY

Active Member

• Dec 7, 2006

• #3

aah that makes sense - thanks!

 

Sceadwian

Banned

• Dec 7, 2006

• #4

Just be careful about power disipation, as it's very easy to violate a POT's power rateing using it as a resistor if you get too close to the low ohm end.

 

Hero999

Banned

• Dec 8, 2006

• #5

In my oppinion potentiometer shouldn't have just a power rating, they should have a current rating. For example 100mW might be alright if it's heating the entire track but not if it's only heating a small portion of it.

 

philba

New Member

• Dec 8, 2006

• #6

just put a fixed resistor in series with the pot. Size it to the max current you want through the pot (or based on other factors in your circuit).