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Old 23rd February 2010, 08:56 PM   #3761
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Quote:
Originally Posted by simon7000 View Post
Wirewounds come very close to zero tempco!
Is that much of a concern in this particular application?

Also, are any of them non-inductively wound? Not sure how you'd pull that off in a potentiometer. And if they're not, how would that inductance effect cartridge loading? They'd certainly be good at picking up stray magnetic fields unless they were well shielded.

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Old 23rd February 2010, 09:03 PM   #3762
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Quote:
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Is that much of a concern in this particular application?
I wouldn't think so- a potentiometer would nearly always be at the same temperature along the track (assuming it's not abused), and it's ratiometric...
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Old 23rd February 2010, 09:16 PM   #3763
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I wouldn't think so- a potentiometer would nearly always be at the same temperature along the track (assuming it's not abused), and it's ratiometric...
Ooooo. Ratiometric. I love it when you talk dirty to me.

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Old 23rd February 2010, 09:42 PM   #3764
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Gets lonely there in Sacto?
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Old 23rd February 2010, 09:47 PM   #3765
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Gets lonely there in Sacto?
Only when you're not here.

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Old 23rd February 2010, 09:59 PM   #3766
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I use multigand trimmers in my circuits to trim for DC and minimum distortion.
Usually i use Spectrol ( now Vishey).
I use them in the signal chain with a resistor parallel. So when i have a resistor of say 470 Ohm i use a 5kOhm pot in parallel ( just an example).
That way i limit the pot range, so when it is a little bit of it is not a tragedy.
Performance wise i am happy with that configuration.
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Old 23rd February 2010, 10:54 PM   #3767
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I hope to use these potentiometers in rheostat mode that will emulate a changing resistance. Therefore, tempco could be important. The digital readout might drift, and upset the customer. I also welcome suggestions of how best to series and parallel fixed resistors for optimum operation.
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Old 24th February 2010, 01:22 AM   #3768
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What about the magnetic resistance wire and inductance? Or are you just talking about pots in general?

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Old 24th February 2010, 03:50 AM   #3769
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The pots that I have looked at have +/- 100 ppm tempco, and are essentially non-magnetic. I would avoid a really magnetic material as the fundamental material in a pots construction.
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Old 24th February 2010, 04:10 AM   #3770
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Quote:
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The pots that I have looked at have +/- 100 ppm tempco, and are essentially non-magnetic.
You talking about wirewounds?

What resistance wire alloy are they using in them?

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