potentiometers (pin1-pin2 soldered together)

I picked up some rheostat type potentiometers for use in a project. I notice that the middle connector is soldered together with one of the side connector. As you know potentiometers have 3 connectors. I am wondering what was the original intend of the person soldering two of the 3 pot connectors together. I know if changes the resistance measured, but in what way?

Reply to
Orc General
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If you are using the pot as a variable resistor (rheostat) and the wiper makes perfect contact with the resistive element, then there is no difference whether or not the wiper is also soldered to the unused part of the resistor. But if the wiper skips over a bit of crud and looses contact with the element, then the difference is that one goes open circuit and the other just has a jump to full element resistance at that spot.

Reply to
John Popelish

It doesn't change the resistance measured by very much. It can improve the apparent CRV a bit, so it's good practice to connect it that way.

Best regards, Spehro Pefhany

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Reply to
Spehro Pefhany

Um, you turn the knob one way and it increases, and you turn the knob the other way, and it decreases?

Seriously, though, that's done to increase the reliability. If, for some reason, the wiper fails to make good contact with the element, then with pin 1 & 2 shorted together, the total resistance only jumps to the max. resistance of the pot, rather than infinity.

Hope This Helps! Rich

Reply to
Rich Grise

That's a 'standard' two wire pot. I see them a lot. Basically the wiper and one end are tied together. The resistance across the paired leads and the remaining single lead varies with angle, assuming a linear pot it will vary linearly with angle. The sole advantage compared to leaving the terminal unshorted is that is impossible for the end user (the one who didn't short the two terminals together) to hook it up wrong. IE it is polarity insensitive. It is otherwise identical to hooking up to the wiper with one wire and the appropriate end with the other.

Hmm, now that I think about it, if the wiper goes open for some reason it also limits the maximum resistance. I don't know if that's useful in any application or not. It's not in the ones I know that use it.

Robert

Reply to
R Adsett

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