Hello,
I am trying to make a Megaphone or a device in which you can speak into a electret mike, the circuit will amplify the signal and use a large speaker to make what you are saying much louder. I breadboarded the circuit from this site:
https://cnx.org/content/m12514/latest/figure14.jpg
The supply I am using is a 12V 1.2A transformer. I just connected a 3 inch 8 ohm speaker to the output. As soon as I turn in on, I get a loud buzzing sound, If I speak into the electret, I can barely hear my voice in the background of the loud buzzing comming from the speaker.
Does anyone know what the problem is or how to fix it?