Being a guitar player, my brother got me one of those guitar shirts for Christmas that has a board with pressure sensors attached to it and an actual miniature amplifier. When the sensors on the board are being pressed, a signal is sent to the circuit within the little amp and a guitar sound is played through the speaker. It also has a three-pin volume pot and apparently some kind of digital tone control. I've attached photos of the amp and the circuit down below.
Of course, the sensors don't really work perfectly and while it was a nice gift and we had some fun with it, I don't see an actual use for it. However, I do see a use for the little amp, since my laptop's speakers don't work anymore and I've considered buying a portable speaker of that size to play sound when I need to (which rarely happens, but it would be helpful for school presentations and such).
Would it be possible to either unsolder the front output jack and solder it back somewhere into the circuit as an auxiliary input to connect a laptop's headphone out to the amp (or connect an additional mini audio jack in that way)?
I would like to "tap" into the existing circuit to use it this way:
Audio Out - Audio Cable - Amp Input - Amplifier/Volume Control - Speaker
Unfortunately, I don't know where the amplifier circuit begins and where I would have to connect the tip and sleeve of an audio input jack.
Can someone here see if and how this could be possible?
Circuit: Orange, green and blue cables connect to power switch, white to the speaker, red and black to the battery (4x AAA 1,5V in series), the 8 pins on the bottom left connect to the board with the sensors and would not be needed anymore.
With Jasen's help, I attached a 3.5mm audio cable to the amp for testing. Unfortunately, I wasn't able to get any sound out of it, so far.
I've connected both signal wires with 10k Ohm resistors in between to the first pin of the volume pot and a ground wire to the output jack's sleeve connection on the amp. All connections make contact (I tested them with a multimeter). At first, I didn't want to cut the original trace on the PCB to the pot, so I just cut the corresponding pin on the pot itself and bent it forward, so that it didn't have a connection to the PCB anymore.
When I turned the amp on afterwards, I just heard a silent hissing sound and no input from my phone which I used for testing. I thought that I had to cut the old trace anyway and cut a small nick into the side of the PCB so that just the outer trace was damaged. Then, I got no sound from the speaker at all anymore. As far as I can tell by measuring the other connections, no other traces on the PCB were damaged.
I also tried to shorten the wires from the audio cable to the pot directly without the resistors, because I thought they may have been rated too high, but that resulted in no change.
Did I do something wrong or is there another way to get sound into the amp?
I've attached another photo of how the circuit looks now down below: