One VR adjust two channel volume.

[Boki]

Hi All,
How to implement one variable resistor to control two channel
volume?

Best regards,
Boki.

 

[Jim Thompson]

Hi All,
How to implement one variable resistor to control two channel
volume?

Best regards,
Boki.

One variable resistor to control two channel BALANCE, easy, "one
variable resistor to control two channel volume", not so easy.

But lots of different ways... perhaps the easiest: use a single pot,
A/D, control two digital pots.

...Jim Thompson

 

[Pooh Bear]

Hi All,
How to implement one variable resistor to control two channel
volume?

Oh come on now !

A dual pot is simpler ! It can all be done 'analoguely'. ;-)

If you want to do it with a single pot, then you digitise the pot setting
and use it send a control word to your DAC.

Graham

 

[Boki]

Please advice TI 1742 can do that or not.

Thank you very much.

 

[Boki]

It seems that will affect the AV output sepc? right?

 

[Boki]

use audio ampilifier is cheaper or opamp by myself is cheaper?

Thank you very much.

Best regards,
Boki.

 

[Pooh Bear]

Please advice TI 1742 can do that or not.

Yes it has a built-in digitally controlled attenuator. You may not
have a spare ADC to read a pot though.

Using a simple 'volume control' arrangement may be a lot simpler
though !

I hope you know how to do that !

Graham

 

[Boki]

Ya, I got it.

Coudl you please advice:

1. the cheapest AD for this application.
2. Does that effect the AV output spec? is that alright?

Best regards,
Boki.

 

[Mac]

Hi All,
How to implement one variable resistor to control two channel
volume?

Best regards,
Boki.

Do you literally mean "variable resistor," or is it a potentiometer with a
wiper? I assume you mean potentiometer.

In any case, you can use a Voltage controlled amplifier. For example the
SSM2164.

The variable resistor would be used to set the control Voltage for the
SSM2164. You will probably need to buffer the Voltage as the control
inputs on the SSM2165 apparently have a 4k input impedance.

HTH.

--Mac

 

[Ban]

Hi All,
How to implement one variable resistor to control two channel
volume?

Best regards,
Boki.

You need a log tapered stereo pot to control 2 channel volume. Or else you
can use a dual digital pot and up/down push buttons.

 

[Pooh Bear]

Do you literally mean "variable resistor," or is it a potentiometer with a
wiper? I assume you mean potentiometer.

In any case, you can use a Voltage controlled amplifier. For example the
SSM2164.

The variable resistor would be used to set the control Voltage for the
SSM2164. You will probably need to buffer the Voltage as the control
inputs on the SSM2165 apparently have a 4k input impedance.

His DAC has an inbuilt programmable attenuator that can control output volume
so doesn't really need any extra devices in the signal path.

Graham

 

[Jon]

Use 2 analog multipliers. The "variable resistor" could control the dc
input to the x(y) input to both multipliers. The audio input would go
to the individual y(x) inputs of the multipliers. This would only work
well for high level signals. Otherwise, noise would be a problem.
This is an expensive solution.

 

[Mac]

His DAC has an inbuilt programmable attenuator that can control output volume
so doesn't really need any extra devices in the signal path.

Graham

Ah. Now I see that there is a relevant history to this question which
precedes this thread. My apologies.

--Mac