Author Topic: Ganged Preset Resistors  (Read 1184 times)

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Offline German_EETopic starter

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Ganged Preset Resistors
« on: March 01, 2019, 09:21:18 pm »
We've all done it, once in a while we've come across a need for something that just isn't made, and now it's my turn.

I need two 20K ohm preset resistors that are ganged together, just like a stereo volume or balance control but a lot smaller. If it doesn't exist then I might get the smallest dual gang pot I can find and cut the shaft off but that's a bit of a hack.

Any ideas?
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Online Benta

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Re: Ganged Preset Resistors
« Reply #1 on: March 01, 2019, 09:50:28 pm »
How small?
Vertical/horisontal?
SMD/TH?
 

Offline German_EETopic starter

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Re: Ganged Preset Resistors
« Reply #2 on: March 02, 2019, 08:38:54 am »
Ideally as small as a couple of normal preset resistors, vertical mounting, through-hole. ALPS make some quite small dual potentiometers which is why I had the idea about cutting down a shaft. Another alternative is a pair of presets with a wheel rather than a screwdriver slot and then carefully glue the wheels together, maybe.
Should you find yourself in a chronically leaking boat, energy devoted to changing vessels is likely to be more productive than energy devoted to patching leaks.

Warren Buffett
 

Offline Gyro

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Re: Ganged Preset Resistors
« Reply #3 on: March 02, 2019, 10:31:31 am »
I can't think of anything other than using a small ganged pot.

It seems a bit of an odd requirement for a preset, it raises questions like what degree of wiper matching accuracy is required? - can't you just put the presets side by side and visually match them?

Presumably these are internal presets rather than external screwdriver slot adjustable?
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Offline beanflying

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Re: Ganged Preset Resistors
« Reply #4 on: March 02, 2019, 10:51:51 am »
Two Vertical mounted Trimmers with side adjustment like below. Place them on the board front face to face with a 3D printed wheel in between with an appropriate blade connecting the slots one to the other or two blades go get the alignment correct if needed. Should be able to be made 2.5-3mm width wheel plus the two pots wide.

The thing you haven't made mention of is what sort of Accuracy or Linearity you need? Pots aren't always as good as you may want.

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Offline duak

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Re: Ganged Preset Resistors
« Reply #5 on: March 02, 2019, 08:11:46 pm »
Piher makes trimpots with an internal hex drive. (see attached image) I don't know if they also make a knob with an extended hex shaft to drive two or more.  Perhaps a plastic hex alignment tool could be found.

Cheers,

 
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Online Benta

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Re: Ganged Preset Resistors
« Reply #6 on: March 02, 2019, 08:14:31 pm »
Piher also supplies the hex shaft. Good idea!
 
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