Can it spin forever, or does it stop. If it keeps spinning, it is some sort of rotary dial.
For the record, some pots can spin forever. They just don't change resistance any more once they hit either rail, but you might be able to feel a light click with each revolution once you hit either limit.
Not saying that this is for sure a pot and not remotely claiming that all pots can spin forever, but some definitely can. They're all over the place on the military circuit cards I used to write test programs for.
[threadjack] I've been looking for that type of continuos pot for a while. Most that I find just cross back to the other extreme causing a huge jump in output from high to low or versa vice. Any links available to a retailer or model number for a pot that spins continuously but maxes out at a value?
I believe most of the 12 turn pots would do what you are looking for. They turn continuously but once they hit there max value at the high or low end they just stay there.
It's literally been like 15 years since I was doing that sort of work so I can't be certain, but I did a quick search on "blue trimpots" and found this link...
http://www.robotroom.com/Trimpots.htmlThe third one from the left in the first pic sure looks like what we used all over the place on the old naval MK45 circuit boards... I can't recall if the ones we used were made by Bourns like the ones in the pic, but other than that they look identical. His text says these are actually 25 turn multiturns... makes sense, we used them to fine tune old analog circuitry to the added precision would have been useful to us. The one in the pic is in stock at Mouser...
http://www.mouser.com/Search/Refine.aspx?Keyword=652-3296W-1-203LFAt $2.50 a pop, they're a bit pricey for a pot IMO, but the 10-turn ones may be cheaper. Or maybe you can find a lot of them on ebay, or find some at a surplus store. I'm about due for another Mouser order, if they were fifty cents a piece I'd pick up a dozen but as it is I might just nab a couple.
I've got lots of pots lying around but since we've been discussing it I'm missing those old trimmers.
Edit: be sure to check the second page of that first link I sent, it shows cutaways of single turn and multiturn trimpots and explains how they work. It even shows a gap in the teeth of the rotating wheel inside a multiturn trimmer that prevents the worm screw from pushing it past one of the rails. Neat. Now, it's entirely possible that a different brand of trimmer might just have continuous teeth on that wheel in which case it would keep turning and WOULD pop back to the other extreme resistance, so a little experimentation with whatever brand you end up with might be a good idea. I checked ebay, there are lots of lots little blue trimmers on there, but most are not Bourns if that matters to ya. I may snag a cheap lot just to see what I end up with.
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Topic: Potentiometer Help (Read 4037 times)
