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 Post subject: Shaftless potentometers
PostPosted: Feb Mon 26, 2018 9:00 am 
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Location: Spring Hill, FL
I'm looking for a potentiometer that would be panel mount, but requires a screwdriver to adjust. I've seen them in quite a few pieces of old test equipment, but I'm not sure what you would call them exactly to search for them now. Either no shaft or a short enough shaft that you can't turn it by hand.

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 Post subject: Re: Shaftless potentometers
PostPosted: Feb Mon 26, 2018 9:10 am 
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Value and watts would help.

Dave


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 Post subject: Re: Shaftless potentometers
PostPosted: Feb Mon 26, 2018 9:25 am 
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4.7K and nothing special on the wattage. It's a low power circuit.

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 Post subject: Re: Shaftless potentometers
PostPosted: Feb Mon 26, 2018 11:39 am 
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Location: Lincoln City, OR
Greetings to Michael and the Forum:

If you have a pot with a short enough shaft with a screwdriver slot in the end of it, you can mount it with a long nut (I don't know the correct term for these, but they are often used to connect two threaded rods together) and this will prevent the shaft from being turned except with a screwdriver. They do stick out from the panel a ways though.

I have four pots in stock that have virtually no shaft and have a split bushing so that the pot can be locked in place after adjusting. I have only two lock nuts for them, however, but I suppose I could part with one. Also, they are all 5K, not 4.7K.... may not work for your use.

I also have two plastic collar nuts that are designed to go over a pot with a short shaft with a slot in the end.... these prevent other than screwdriver adjustment but they can be unscrewed by hand to expose the pot shaft for finger adjustment. I hate to part with anything I only have one or two of, but I suppose I could be persuaded to part with one.

All of these options stick out a bit from the panel, however... none is flush with the mounting nut.

Let me know if you are interested or need photos.

Regards,

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 Post subject: Re: Shaftless potentometers
PostPosted: Feb Mon 26, 2018 7:51 pm 
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Location: Charleston, W.Va.
Hi TPAairman,
I am not sure of exact name for these either, but we have all seen them before. Often in test equipment and on the back of vintage TV's.

If Jthorusen does not have what what you need, I suggest you contact Mark Oppat: www(dot)oldradioparts(dot)net

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 Post subject: Re: Shaftless potentometers
PostPosted: Feb Mon 26, 2018 8:24 pm 
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Poston Drake wrote:
Hi TPAairman,
I am not sure of exact name for these either, but we have all seen them before. Often in test equipment and on the back of vintage TV's.

If Jthorusen does not have what what you need, I suggest you contact Mark Oppat: www(dot)oldradioparts(dot)net
They are generally referred to as a trim pot, trim potentiometer, or a trimmer potentiometer.

Curtis Eickerman

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 Post subject: Re: Shaftless potentometers
PostPosted: Feb Tue 27, 2018 10:24 pm 
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Location: Florida
You can make one from a regular pot with a hacksaw.

RRM


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 Post subject: Re: Shaftless potentometers
PostPosted: Feb Tue 27, 2018 11:20 pm 
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Let me Google that for you:
"slotted shaft pots"


https://www.mouser.com/ProductDetail/Ho ... bsQAvD_BwE
Image

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 Post subject: Re: Shaftless potentometers
PostPosted: Mar Sun 04, 2018 7:03 am 
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Location: 253 Blanche St. Plymouth, MI USA
I have most any kind you might want. The one Peter shows has a slotted bushing so that the setting can be fixed in place by installing a nut that locks the shaft. This type is used in industry and was found in military gear too.
Mark Oppat


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 Post subject: Re: Shaftless potentometers
PostPosted: Mar Sun 04, 2018 7:11 am 
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Reminds me of the old country song: "She got the gold mine ... I got the shaft."

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 Post subject: Re: Shaftless potentometers
PostPosted: Mar Sun 04, 2018 8:10 pm 
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Pbpix wrote:
Let me Google that for you:
"slotted shaft pots"


That's one of the few terms I didn't try. I also didn't think of looking for a trimmer pot. I'll give that a go.

In the mean time, I found a bag of pots that I bought on Amazon quite some time ago and forgot I had them. So, one of them met the business end of my dremel. I wired it up, but before mounting it, I gave the circuit a test run, and all was well. I mounted, and now it was dead. I found out if I slightly moved the wires, it cut in and out. I pulled it, and using my meter found it was a problem in the pot, though the leads themselves were tight. I chalked it up to a defective pot. So another one got introduced to the dremel, and same thing. Just a reminder of why I don't normally order parts from Amazon. I can't recall why I got these for that matter.

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 Post subject: Re: Shaftless potentometers
PostPosted: Mar Sun 04, 2018 9:59 pm 
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Location: Haledon, NJ, usa
TPAairman wrote:
Pbpix wrote:
Let me Google that for you:
"slotted shaft pots"


That's one of the few terms I didn't try. I also didn't think of looking for a trimmer pot. I'll give that a go.

In the mean time, I found a bag of pots that I bought on Amazon quite some time ago and forgot I had them. So, one of them met the business end of my dremel. I wired it up, but before mounting it, I gave the circuit a test run, and all was well. I mounted, and now it was dead. I found out if I slightly moved the wires, it cut in and out. I pulled it, and using my meter found it was a problem in the pot, though the leads themselves were tight. I chalked it up to a defective pot. So another one got introduced to the dremel, and same thing. Just a reminder of why I don't normally order parts from Amazon. I can't recall why I got these for that matter.

Is it an audio taper pot needed or a linear taper?
The link I showed above is for a "Linear taper"

If you tried using an audio taper where linear was needed you would experience weird results.

Linear pots change/vary the resistance in a linear fashion
Audio pots change/vary the resistance in a logarithmic manner.

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 Post subject: Re: Shaftless potentometers
PostPosted: Mar Mon 05, 2018 6:38 am 
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It needs to be linear and that's what I used.

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 Post subject: Re: Shaftless potentometers
PostPosted: Mar Mon 05, 2018 6:52 am 
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Location: 253 Blanche St. Plymouth, MI USA
Have nominal "5K" linear here, can put any shaft you want on it. Email me *****
Mark Oppat


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