Hello there everybody!! I have some electret microphones which I want to test-whether they work or not, since they are pretty old now. Can you please recommend a simple circuit with which I can test the mic? I also want to make a circuit using NE555 to which would amplify all that I will talk to the microphone- to the speaker so that I can hear my voice from the speaker.

Thanks in advance for your help!!

 

So, does that mean that there are no such circuits using NE555?

 

555 is more of a switch/timer than an amplifier.

If you have a transistor, you can test it. Electret microphones need a bias voltage, very low current at 2-5V is typically used. The output can then feed a single transistor.

Here's a very basic circuit for an electret microphone, follow the thread for a better one.

Install free SoundCard Scope to see the waveforms.

I gave a bit of direction on using SoundCard Scope in This thread Just remember to include the voltage divider and diodes so you don't damage your computer sound card input.