Install a potentiometer to control volume TDA7492 board

[Chrispy61]

That's brilliant. Thanks for the helpful replies

 

[KrX]

Hi i got another question since i tried it and it didnt really work. since my cheap amp didnt arrive yet to canabalize the log pot so i tried it with an liniar pot 50k ohm. when i wire it up as below i can change the volume but not much. at minimum it is already loud and going to maximum it just get a bit louder. how much ohm should i use for testing it if 50k is wrong?

my wireing:

i asume that those pins of the bluetooth module are (left and right arent dont really matter):
SPK_AP -> left speaker +
SPK_AN -> left speaker -
SPK_BP -> right speaker +
SPK_BN -> right speaker -

AP -> P for Power; AN -> N for Neutral /ground

 

[ICG]

Well, you've got it quite wrong. Firstly, you need a log potentiometer, otherwise you only have a very narrow angle in which it changes the volume significantly. Secondly, your wiring is wrong. The gnd of the source is connected to one of the outer potentiometer pins and continues (or parallels) to the board. The 'hot' (or '+') wire goes to the other outer pin, the middle it the output.

-> Lone Wolf Blues Company Technical - Mic Volume Control

 

[nigelwright7557]

Well, you've got it quite wrong. Firstly, you need a log potentiometer, otherwise you only have a very narrow angle in which it changes the volume significantly. Secondly, your wiring is wrong. The gnd of the source is connected to one of the outer potentiometer pins and continues (or parallels) to the board. The 'hot' (or '+') wire goes to the other outer pin, the middle it the output.

-> Lone Wolf Blues Company Technical - Mic Volume Control

Post 22 diagram is correct.
He just needs a log pot.

 

[scottjoplin]

The chips outputs are differential, so you can't connect the negative sides together or use a potentiometer as you have done.

 

[KrX]

Well, you've got it quite wrong. Firstly, you need a log potentiometer, otherwise you only have a very narrow angle in which it changes the volume significantly. Secondly, your wiring is wrong. The gnd of the source is connected to one of the outer potentiometer pins and continues (or parallels) to the board. The 'hot' (or '+') wire goes to the other outer pin, the middle it the output.

-> Lone Wolf Blues Company Technical - Mic Volume Control

thats exactly how i wired it or am i not seeing right?

Post 22 diagram is correct.
He just needs a log pot.

so from both posts my only mistake is the liniar potentiometer, so i will wait for the log pot to arrive and test it again.

The chips outputs are differential, so you can't connect the negative sides together

thats why i connected them seperately

or use a potentiometer as you have done.

so you meant that it wont work that way with a pot?

 

[scottjoplin]

You could try wiring the pot as a variable resistor across the differential outputs. Include resistors before and after the VR so the circuits don't see a short

 

[KrX]

You could try wiring the pot as a variable resistor across the differential outputs. Include resistors before and after the VR so the circuits don't see a short

the log pot arrived today and i tested it again (wireing like in my post above) and it works good

 

[scottjoplin]

That's good, are you able to turn the volume all the way down now?

 

[KrX]

That's good, are you able to turn the volume all the way down now?

yes at minimum i dont hear anything, and going to max the volume gets louder smothly

 

[scottjoplin]

when i wire it up as below i can change the volume but not much. at minimum it is already loud and going to maximum it just get a bit louder.

When you said minimum you didn't mean all the way down?

 

[KrX]

When you said minimum you didn't mean all the way down?

yes i mean with minimum all way down, and maximum all way up

 

[scottjoplin]

In that case I'd be interested to know why with first pot all the way down you still had sound and yet with the new pot you didn't.

 

[nigelwright7557]

In that case I'd be interested to know why with first pot all the way down you still had sound and yet with the new pot you didn't.

Maybe one input is grounded ?

 

[scottjoplin]

Perhaps, but it doesn't explain why the first pot didn't turn the volume all the way down. Actual pictures of what he's done would help, but it's too late for the initial set up now unless he's also interested to find out why.....

 

[nigelwright7557]

Perhaps, but it doesn't explain why the first pot didn't turn the volume all the way down. Actual pictures of what he's done would help, but it's too late for the initial set up now unless he's also interested to find out why.....

If the pot was wired with the centre pin as audio in and outer pin as audio out it might not go all the way down.

 

[KrX]

no it was my mistake, i did only wire one ground to the pot not both. so i could reduce the sound of one speaker while the other was still as loud as before and i thought it didnt work. after some time i realized that at minimum one speaker was "off" and than i realized my mistake.

so i didnt wire it exatly as in the picture at first. when wireing it exactly like in my picture it works

 

[Chrispy61]

Can you buy potentiometers that can also switch the device on and off? If so what are they called as I can't seem to find one

 

[KrX]

like this one

High Quality B50K 50K Ohm Dual Linear Taper Volume Control Potentiometer Switch-in Switches from Home Improvement on Aliexpress.com | Alibaba Group

but this is a liniar one and you need a logarithmic one

 

[clemcoste]

Hello everyone,

It is possible to re-upload the image of the post #22 please ? Or describe how it is wired ?

Thank you very much