Electronics > Projects, Designs, and Technical Stuff
Potentiometer Suckage
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engrguy42:
So I wanted a quick adjustable voltage divider for a 10 volt source, so I reached into my boxes of components and grabbed one of those cheap potentiometers (see image). It was like 5k, and I assumed yeah, not a problem since that's only like 2mA thru the full resistor.

Well, not so much. Now the thing is all flaky and inconsistent and probably got zapped somehow. Okay, I should have used a decent wirewound in the first place, but I'm a wildman. A renegade. I throw caution to the wind.

Anyway, I'm curious if anyone knows if these things have any sort of rating that would clarify exactly what their capabilities are. I'm sure part of the problem is mechanical too. Depending on how hard you press when you turn affects the value or whether it's open circuit. BTW, I tried this on another one and got the same results. 

Thx.
 
bob91343:
That cheap part is wide open and has no protection from dust or mucking with the contact spring.  You might have to clean the element with some solvent.  Are you drawing current from the wiper?

I don't understand what problem you are having.
engrguy42:

--- Quote from: bob91343 on May 29, 2020, 05:44:13 pm ---That cheap part is wide open and has no protection from dust or mucking with the contact spring.  You might have to clean the element with some solvent.  Are you drawing current from the wiper?

I don't understand what problem you are having.

--- End quote ---

Bob, baby...I took the cover off so you could see what I'm talking about.  :D  It has a cover.

Anyway, I just hooked it up to a 10V source across the entire pot, then connected the tap to an IC circuit (no amps drawn) to apply variable volts. The output voltage from the pot was flaky and not smoothly variable. 
Yansi:
Problem is not with the wiper contact, but with your soldering.  ;)

You got excessive flux under the overheated riveted lugs, creating intermittent contacts. This is a well known failure mode with this style of pots. No matter which brand. 



engrguy42:

--- Quote from: Yansi on May 29, 2020, 05:48:59 pm ---Problem is not with the wiper contact, but with your soldering.  ;)

You got excessive flux under the overheated riveted lugs, creating intermittent contacts. This is a well known failure mode with this style of pots. No matter which brand.

--- End quote ---

Yeah, that makes sense. Us old guys with our crappy eyesight.

Thanks.
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