This circuit used to work before I soldered it. When I initially soldered it, I used a 6V battery and it was oscillating, but the speaker was very quiet. I went with a 9V battery and I re-soldered some other parts because the speaker would still not produce any sound. As well, the LED would have a voltage of around 8V on its turn while the speaker would only have around 0.03V on its turn (this stayed the same even after I switched their places and even replaced them). Right now, the speaker makes no sound and the LED (which previously flashed up with each oscillation) no longer flashed either. I checked with a voltmeter and voltage was still there across the circuit and across the loads. I can assure you that no soldered part is touching another (I know this cuz I've spent a day looking at them).
I don't know what to do make the circuit function and for the speaker to make sound, please help.
Best Answer
For loud sound you cannot drive the speaker through such a high impedance like 2k2. Also, your oscillator works at too low frequency (10Hz if pots are down) so it acts like a DC signal.
The circuit I attached below oscilates at about 1kHz and drives the speaker with higher power so the sound should be louder. Try to change C3 a little if necessary.