I'm trying to transfer sound from an electret microphone to my speaker.
I'm copying a simple circuit from the Internet with 5V source from USB and a 1Kohm resistor. However, because I don't have a capacitor here, I removed it from the circuit.
The output is connected directly to the speaker. After finishing it, I tested my project by saying some words into the electret microphone. It can reproduce my voice when I bring my mouth very close to the microphone and talk 'uuuuuuuuu' 'aaaaaaaaaaa'. It can record my breath when I blow to it. But it cannot reproduce any other sound around me or 'real human voice' as a working microphone. What am I doing wrong in my project?
Best Answer
The eletret microphone requires a dc bias to enable it to function. However, you only need to detect the audio (ac) signal to amplify and feed to a speaker. The capacitor blocks the dc bias, whilst passing the audio signal to the amplifier. There must be an amplifier to generate the required power to drive the speaker. The speaker will have a low impedance, typically 8 to 16 ohms. The amplifier must provide the power and a matching output impedance _ else won't work!