I am trying to make an audio amplifier using one op-amp and 5 V supply. The problem lies with the identification of the microphone,whether it is an electret,condenser or some other type. I bought it from a general audio spares shop for a cheap rate, small enough (size of a fingertip) to fit on a breadboard. I searched a lot on the internet to identify a similar looking device, all they have is the pictures of electret microphones. Now I am confused as the type of microphone is very essential to start my design,because some have a FET preamplifier inside, some need a bias voltage,etc. It is cylindrical with black plastic sides and metal exposed on top and bottom. There are 5 small holes on the top at the centre. At the bottom two pins come out. The juncture of one of the pinsis encircled with black paint .

Please can anyone look at the picture and tell me the type and its specifications ?

 

Simply first assume that you have a electret microphone with a built-in JFET and do the practical test on the breadboard.

 

Simply first assume that you have a electret microphone with a built-in JFET and do the practical test on the breadboard.

But if so , what value of resistance should i connect from the supply to the mic. for the built-in pre-amp, so as not to damage it ?

 

So you didn't watch the video? Use 4.7K for example.

 

I am trying to make an audio amplifier using one op-amp and 5 V supply. The problem lies with the identification of the microphone,whether it is an electret,condenser or some other type. I bought it from a general audio spares shop for a cheap rate, small enough (size of a fingertip) to fit on a breadboard. I searched a lot on the internet to identify a similar looking device, all they have is the pictures of electret microphones. Now I am confused as the type of microphone is very essential to start my design,because some have a FET preamplifier inside, some need a bias voltage,etc. It is cylindrical with black plastic sides and metal exposed on top and bottom. There are 5 small holes on the top at the centre. At the bottom two pins come out. The juncture of one of the pinsis encircled with black paint .

Please can anyone look at the picture and tell me the type and its specifications ?

Most electret mics require a supply, either a battery compartment in the case or a stereo type jack so +5V can be supplied to it via its lead - the uncased bare component mic is a small capsule, usually about 10mm diameter (much smaller in mobile phones).

A crystal mic has massive resistance, probably too high to measure, they usually exhibit some capacitance.

A dynamic mic has probably no more than couple of hundred Ohms - likely far less, it will be inductive.

A carbon mic will probably be heavier and bulkier - probably also near 200 R, hook it up to a resistance meter and blow into the sound hole - you should be able to lower the resistance reading.

For a low impedance mic - consider a common base transistor input stage, its a better impedance match and plenty of voltage gain.