This is the tested and proven circuit.
After learning the Electret Mic has a polarity and getting it wired correctly with the 10k, 1k and 100uf cap it works. I am surprised this little Electret mic it has a good sound and good pickup.
Sound quality is very bad lots of distorted.
I removed the capacitor between pin 1 and pin 8 that made a very big inprovement in sound quality gain drops to 20. Volume control in series with cap was not very much improvement and different size caps are no help either.
The 10k variable resistor is useless, turn it just a little and there is no sound at all. So I replaced the variable resistor with a fixed resistor. I should have experemented with a 20k, 50k and 100k variable resistor.
The 10k resistor needs to be connected directly to pin 3 with no capacitor between pin 3 and the resistor.
The .1uf cap between pin 3 and the mic works perfect, I experemented with several other caps .1uf works best.
I experemented with the 100 uf cap at the ear phone, I changed it from 50 uf, 100 uf, 350 uf, 470 uf all this does is make the signal have lower Hz base sound and no effect of the bad quality sound.
30 years ago I use to know what the bypass capacitor on pin 7 is for but I can no longer remember and don't remember where too look it up. I removed the .05uf cap and sound quality appeared to be worse so I tried several caps even a 10uf then finally went with a .1uf cap.
After several parts swapping experements sound quality is 100% better. Sound is best with a brand new 9v battery.
**broken link removed**