Potentiometer - Eureka Moment

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don87109
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Potentiometer - Eureka Moment

Post by don87109 » Sat Feb 02, 2019 9:14 am

For all my years I have used pots and never really recognized an obvious drawback...there's no way to tell what value the pot is set at. Okay, maybe I recognized the drawback but just accepted it.

A few days ago I was rummaging though my ample junk box and discovered a multi-turn pot with a dial indicator that displays the setting of the pot. I had a eureka moment...holy crap all these years and I never recognized the convenience of this pot lying in my junk box. I quickly mounted it in a little box with some binding posts and now use it frequently.

I can't believe I never did this before. I can even remember years ago building a switchable resistance substitution box. For development purposes it's hard to beat this type of pot unless you need extreme precision or perhaps higher wattage. It might even work as permanent control for some projects where the resistance is proportional to whatever the pot controls...

A quick Google search found several such pots at reasonable prices...including ebay and Aliexpress.

Probably most people here are smarter than me and know this already, but there may be a few like me so I figured I'd post this note.

Hope it helps..

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haklesup
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Re: Potentiometer - Eureka Moment

Post by haklesup » Mon Feb 04, 2019 11:10 am

I suppose you are talking about a 10-Turn Pot with a mechanical Counting Dial?

You can know the value as a function of dial setting but you probably need to create a calibration curve and use it to lookup the value.

If you always use a pot as a voltage divider where very little current flows through the wiper, you should be OK. In which case, wattage applies to the current flowing through the two main terminals, you should still keep the wiper current low by either placing another series resistor in the network or by applying it to the input of a low current next stage circuit (like and op amp).

https://www.alliedelec.com/product/bour ... lsrc=aw.ds

don87109
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Re: Potentiometer - Eureka Moment

Post by don87109 » Sat Feb 09, 2019 8:33 am

Yes, I was referencing a 10 turn pot with a mechanical counting dial.

The one I found in my junkbox was really excellent. It was made by Bourns many years ago and it's easy to read...and even mounts from the back avoiding the minor complication of zeroing the dial since that is not removed for mounting. Some of the newer styles, like in your link, require removing the dial to mount and I also found them harder to read given my old eyes, but still usable.

Even some one-turn pots come with dials and can be similarly useful, but just not as precise.

Thanks,
Don

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