Buzzing Audio and Potentiometer Not Working

[kamon]

First of all, just want to thank everyone for always being more than willing to help with my problems!
Would've have progressed this far without you all .

So, after fussing with it for weeks and several reworks, I finally have my mono audio setup working.
Just two more things I need to figure out and then I'll be golden.
The first is that my potentiometer isn't working...at all. It's in-line and passing along the signal, but not actually changing the volume.
The second is I'm having some audio noise/interference/buzzing that constantly happening. It isn't as noticeable when the audio is turned up all of the way, but it's still at an unacceptable level. I'm used to some buzzing from older electronics, but this is a lot.

My setup is as follows(sorry for no schematic).

GPIO Pin 18 -> Low-Pass Filter(From Wermy's Guide) -> Pot -> Amp -> Headphone Jack -> Speaker

Is it because my pot is before my amp and it's just boosting the variable signal from the pot into one, flat signal? I'm using the PAM8403 stereo amp. Looking at Wermy's guide, it looks like that's how his pot is too, but I may be wrong.

Thanks in advance for any help!
Really am excited to get this part of my project finished as I've spent forever on it, so crossing my fingers for some awesome advice.

[rodocop]

Not sure why the pot isn't working. Maybe some pictures of your wiring would be helpful?

One other thing. In your last post I mentioned to turn the volume control up in emulation station. I forgot to mention that the amp you have should have its own small pot that you can adjust with a small screwdriver. Adjust that a bit, it should help with the static, or at least make it even less noticeable. I have not been able to eliminate the static completely on mine.

[n.marek]

First of all, just want to thank everyone for always being more than willing to help with my problems!
Would've have progressed this far without you all .

So, after fussing with it for weeks and several reworks, I finally have my mono audio setup working.
Just two more things I need to figure out and then I'll be golden.
The first is that my potentiometer isn't working...at all. It's in-line and passing along the signal, but not actually changing the volume.
The second is I'm having some audio noise/interference/buzzing that constantly happening. It isn't as noticeable when the audio is turned up all of the way, but it's still at an unacceptable level. I'm used to some buzzing from older electronics, but this is a lot.

My setup is as follows(sorry for no schematic).

GPIO Pin 18 -> Low-Pass Filter(From Wermy's Guide) -> Pot -> Amp -> Headphone Jack -> Speaker

Is it because my pot is before my amp and it's just boosting the variable signal from the pot into one, flat signal? I'm using the PAM8403 stereo amp. Looking at Wermy's guide, it looks like that's how his pot is too, but I may be wrong.

Thanks in advance for any help!
Really am excited to get this part of my project finished as I've spent forever on it, so crossing my fingers for some awesome advice.

Did you test it without the filter? I have a different Amp than Wermy, and the filter caused problems, and works fine without it...

[kamon]

Thank you for the info, guys!

I tried it without a filter and it was a bit worse, so that's a no-go there .
And, unfortunately, my amp doesn't have a pot on it.
Would be awesome if it did, though!

Okay, so this just got a little weirder.
I moved the pot from being between the filter and the amp to between the amp and the headphone jack and my buzzing went completely away. But, it got considerably quieter, so much so that I can't really hear anything from the speaker, only a pair of headphones...and the pot still isn't working, just basically passing along the audio...
The buzzing could be from the audio being TOO loud, or maybe a wiring problem, but I've come to the conclusion I can live with the buzzing if I could figure out why my pot isn't working.

I have a standard 10k pot, that I believe follows this schematic:
https://cdn.instructables.com/FGM/Z53Z/ ... MEDIUM.jpg

I have my right out from my amp on pin 2 of the pot and ground out from the amp on pin 1 and out to the headphone jack on pin 5 and ground coming from pin 1.

My headphone jack is working correctly, just not loud enough now... So has to do something with the pot.
Hmm.

[rodocop]

I tried it without a filter and it was a bit worse, so that's a no-go there .
And, unfortunately, my amp doesn't have a pot on it.
Would be awesome if it did, though!

Ah, just re read your first post, and see that you listed PAM8403 as the amp. I am using the PAM8402 amp, which does have a small pot. Sorry for the incorrect info.

Maybe just try another pot? Or have you?

[FreddyMro]

The first time, my pot didn't work either. I received 5 in a package so I tried another one and it worked. I think that I broke it because I soldered much onto it so it probably got very hot what it didn't really like.

So try it with another one and when you soulder it give it a time to cool down a bit after each pin. Maybe that helps. That's what worked for me

[FreddyMro]

Oh okay it also seems to me that your wiring could be wrong. I had a couple of issues with my pot wiri ng until I decided to do it differently from what all people said and it worked. Maybe there's some disadvantage (from which I don't know) but it worked at least.

So on a normal potentiometer you have 3 pins. The middle pin, a right and a left pin. When the potentiometer is fullly turned to one side, the impedance between the middle and one outer pin (depending on which side you have it turned to) is 10kOhm. The impedance between the middle and the other outer pin is then 0. If your pot is exactly half turned then your impedance between the middle and the left as well as between the middle and the right is 5kOhm. A 5 pin pot isn't different except for that you now have ONE left pin (1), TWO middle pins (2&3) and TWO right pins (4&5).

What you can do is, connect only the positive wires to the pot and connect the ground wire (negative) directly from the board to the headphone jack. So your impedence is only created between your positive wires (I still don't get why and how other solutions work). If you have one positive mono cable coming from your board, connect it to pin 1 on your pot (even though it says ground but it can be basically something else). Then connect your left and right positives to the headphone jack to pin 2 and pin 3. That should be it then. And important: No ground to the pot. Connect it directly from the board to the headphone jack. If that doesn't work either connect the outputs to 4 and 5 instead of to 2 and 3. I don't know it for your pot but I think 2 and 3 works. If not, use 4 and 5 instead

Keep working, I know such things are frustrating. But in the end you have something very nice!

[kamon]

Fantastic news, guys!
After having so many issues with this, I finally, FINALLY, have got everything working as intended!

Thank you guys so much for the help and encouragement!

@FreddyMro I didn't end up using your solution, but you got me really thinking that I had the pinout for my pot wrong...turns out, that's totally the case. The B103 potentiometer (here's an amazon link, if people are wanting pictures: https://www.amazon.com/16x2mm-Double-Ta ... 00O9Y6Z70/) has an almost swapped pinout.

Here's an updated pinout, for anyone with future issues!

b103 pinout.jpg (48.77 KiB) Viewed 11023 times

FINALLY I CAN MOVE ONTO THE REST OF MY PROJECT, WOOHOO!