Electronic (electret?) replacement for crystal Microphone

Thank you very much Mr. Woodgate. As I need to work on very small devices, I have to use discreet components, as transistors, and I *think* that the output has to have a very high impedance... As I'm new to newsgroups, I don't know if it's possible to attach a schematic... Regards, Nina

I read in sci.electronics.design that nina.p20 wrote (in ) about 'Electronic (electret?) replacement for crystal Microphone', on Mon, 15 Aug 2005:

Electret is best. Cheap and quite good performance. You need to add a simple op-amp with 20 to 40 dB gain, depending on what sensitivity of the crystal mic your project designer assumed.

Of course, you don't need to feed the op-amp output into such a high impedance as the crystal mic needed, but there is no need to modify that input circuit unless you want to.

I read in sci.electronics.design that nina.p20 wrote (in ) about 'Electronic (electret?) replacement for crystal Microphone', on Mon, 15 Aug 2005:

A discrete transistor amplifier will take up a LOT more room than an op-amp.

No, it doesn't, unless the rest of your circuit uses a rather uncommon technique (capacitive feedback or 'charge amplifier').

It is possible to put 'ASCII-art' diagrams on this newsgroup, but real graphics have to be put on alt.binaries.schematics.electronics.

I think you should tell us exactly what you are trying to do. It sounds like a project beyond your current grasp of electronics. I say that not to insult you but to prevent you being disappointed or even running into really serious problems.

The key rule is that an electret microphone requires a dc bias. Typically +5 volts through a 3.3K resistor.