at the moment I'm trying to amplify an AUX-Signal with a 12V DC supply
voltage. I tried die setup from Here's here as u can see in the sketch below.
simulate this circuit – Schematic created using CircuitLab
But all I get is just an annoying noise sounding horrible.
For the amplifier I used both the CA3240EZ and the OPA134PA.
Maybe my grounds are not connected correctly.
It would be awesome, if anyone could help me out.
EDIT 1:
According to your hints, I tried now those variations of power supply bypass capacitors
1st:
2nd:
EDIT 2:
The voltage is pretty stable at 12,18V as far as I can measure it with my voltmeter.
I changed now the 22kΩ into a 2,2kΩ resistance, so the gain should be 1.
As i decrease my volume the noise also decreases. And if I have volume = 0, one cannot here anything out of the subwoofer.
I still get this annoying sound. I recorded it with my handy and you can listen to it here: https://soundcloud.com/pixel_95/subwoofer-noise
EDIT 3:
I get the via an normal chinch cable going into the receiver of a LG HT44S (www.amazon(dot)de/LG-HT44S-Heimkinosystem-HDMI-schwarz/dp/B003BYQ74A). From there i use the subwoofer output with the orange and black cable as you can see here: i.imgur(dot)com/Aw0hmfr.jpg
Then this black and white cables go into my breadboard in here:
Other View of the breadboard here:
And afterwards the outputs goes to the subwoofer in here:
I put AUX IN normally to my receiver and set the volume to 0. then inverted, non inverted and output are ALL at 6,1V to ground.
Best Answer
Answer
You didn't tell us you were trying to drive the loudspeaker directly from an low-power opamp!
Figure 1. Extract from the CA3240 datasheet showing that the most you can get out of the device is 11 mA (since you need it to both source and sink current).
The opamp is can supply < 100 mW into a high impedance load. Your speaker shows a 3 Ω load.
You need a power amplifier.
History of debug
This is not really an adequate technical description of your problem. It could mean anything from a permanent buzz or hum to gross audio distortion when playing music.
Step 1: Short out your input terminal to ground. The output should be silent. If the noise persists then it points to a power problem or faulty connection. Is your 12 V supply adequate and is the voltage stable?
Step 2: Your original amplifier has a gain of \$ \frac {22k}{2k2} = 10 \$ and if your input signal is large you may be driving the amplifier into clipping. Use a source with adjustable volume control. Turn the volume down to zero, connect up and gradually increase the volume. If this solves the problem then reduce the gain of your amplifier.
The sound sample you posted shows that "music" is in fact getting through but that it is heavily distorted with a characteristic clipped sound. (i.e., The output is hitting V+ or GND and being squared off.
Step 3: Measure the voltage between non-inverting input and ground. It should be 6 V or so and steady!
Step 4: With the input shorted measure the voltage between the opamp output and ground. It should also be 6 V or so.
This is the cause of the distortion!
Step 5: Assuming the opamp is working, for the output to go low it means the voltage on the inverting input must be higher than the 6 V on the non-inverting input. Something is pulling the signal input high. What is the voltage on the inverting input?
Is it time to add a photo of the setup to your post?