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What potentiometer to use as audio control in car stereo? Answered

Hello all

I am working on installing a tablet into my car instead of the original head unit. But since the tablet will be permanently mounted inside the dash, I have no way of turning the volume up or down on the tablet, therefore I need to install a potentiometer into the audio cable that goes into my amplifier. 

I have tried with a dual LIN 100kOhm potentiometer, which worked to an extend, but not as well as I had hoped. 
It did turn the volume up and down, but it couldn't turn the volume all the way down as I had hoped it would be able to.

I just want it to be able to turn up quite loud, but also turn all the way down, so I don't have to pause the music everytime I want it to be quiet. 

Cheers!

Mathew

10 Replies

user
Josehf Murchison (author)2017-04-22

How did you wire in the pot 1. 2. or 3.

Click on the Image to see all three.

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user

I'm not 100% sure, as I have used this for reference as to how to wire it.

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iceng (author)Mat_Holm2017-04-24

If shield is signal ground input then it will work..

If shield is chassis connect and signal ground is different then it won't work !

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user

OK so you have 3 wires from your tablet.

One wire should go to ground.

The other two should go to channel a signal and channel b signal.

Channel a shield and channel b shield should go to ground.

Then the two inside pins should go to to the amp with a ground wire.

Like this schematic with three wires from the tablet and three wires going to the Amp.

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iceng (author)Josehf Murchison2017-04-22

Sounds like a variation of # 1, because Mat said

he "couldn't turn the volume all the way down"..

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Josehf Murchison (author)iceng2017-04-23

That's what I was thinking also.

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iceng (author)2017-04-20

+1 to each D. J. S.

The way to get noisy turn static out of a used pot is to drop a bit of CarbonTetraChloride fluid into the wiper track of the pot, is all that I can add.

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steveastrouk (author)2017-04-20

You need a LOG or audio taper pot as a volume control.

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Jack A Lopez (author)2017-04-20

The phrase is, "worked to an extent". "extent" is a noun. "extend" is a verb.

Anyway, the signal coming out of your tablet is probably intended for driving headphones, and there exist potentiometers for attenuating headphone audio.

Some headphones come with a little thumb wheel potentiometer built into a little plastic bulge in one part of the headphone cable itself.

This instructable,

https://www.instructables.com/id/Universal-EarbudH...

considers a few different ways to wire a potentiometer, volume control knob, into a headphone cable.

By the way, if all you want is to know is the size (in ohms), and character (linear taper, or log taper) of this kind of potentiometer, I think I have a few of these heaphone-cable-lump style pots, in my box of dumpster-scavenged, broken headphones.

Upon request, I can put the multimeter probes on, one or more, of these, for to give you some numbers about their electrical characteristics.

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Downunder35m (author)2017-04-20

Use a potentiometer with build in switch ;)
Getting hard to find these days but were and still are used in small analog and portable radios...

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