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Old 5th January 2010, 02:02 PM   #1
riboli is offline riboli  Italy
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Default potentiometer and led

hello
I have a problem I would like to include in the volume control a strip of LED indicators
I have to take a potentiometer with 3 outputs, or can I use a stereo one ?

Thanks to all
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Old 6th January 2010, 05:03 AM   #2
Enzo is offline Enzo  United States
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Do you want the LEDs to simply tell you where the knob is pointed or do you want them to indicate the signal level?
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Old 6th January 2010, 08:05 AM   #3
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Quote:
Originally Posted by Enzo View Post
Do you want the LEDs to simply tell you where the knob is pointed or do you want them to indicate the signal level?
I do think he means to indicate pot position.

Riboli, you may think to combine two pots linking shafts instead of one dedicated ( maybe one stereo of good quality and one poor for led strips ? )

Never tried but it could works !
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Old 6th January 2010, 10:22 AM   #4
riboli is offline riboli  Italy
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I want to indicate the position.

My idea was to use a pot with 3 outputs, 2 for audio and one for the position but it's hard for me to find it.

then I thought about using stereo potentiometer for volume and also for the position by entering an offset to the signal of +5 V and using two filters to send the audio signals (to the amplifier) and continues for the position (to the uC ) .. .

you think it will work or is a bad idea?

thanks roberto
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Old 6th January 2010, 10:37 AM   #5
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A 3 section pot might be hard to find,perhaps a 4 section pot would be easier? Maybe a second pot linked mechanically,
Use a LM391x IC,then you can choose between bar or dot mode.

Last edited by DigitalJunkie; 6th January 2010 at 10:39 AM.
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Old 6th January 2010, 11:35 AM   #6
Mooly is offline Mooly  United Kingdom
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It's a bad idea to pass DC through a pot that's carrying audio... it makes them very noisy as you turn them.

No easy way... you could mix a low distortion HF signal (100khz say) with the audio and use a notch filter to recover the HF and then fectify and use that to drive a level indicator.
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Old 6th January 2010, 01:30 PM   #7
riboli is offline riboli  Italy
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I understand... I think I will use a pot with 4 outputs and the LM3914 IC or
I found this component PGA2311PA Datasheet - +/-5V Stereo Audio Volume Control PGA2311PA so in the future will also insert a remote control

thanks!
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Old 6th January 2010, 06:18 PM   #8
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Quote:
Originally Posted by DigitalJunkie View Post
Maybe a second pot linked mechanically,
Exactly as i suggested.

I think that the main advantage is to use a very good pot for analog volume and a poor ( read cheap ) for the visualization function.

Dunno about quality of double stereo pots ( and costs )

Riboli, I also thought to do a thing as you want to do, in my case mechanical link is a must cause i use a stepped attenuator instead of pot
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