This amplifier uses a microphone to electret microphone capsule, but can be used can be used and dynamic microphones, which have a low resistance.This circuit requires a supply voltage between 5 and 10 volts, is recommended to use a supply voltage of 9 volts DC .Since the assembly has a very low power consumption (about 1.5 mA), installation can be powered using a 9 volt battery. The values for R1(2k2), C3(47uF) and R8(8k2) are for electret capsule.
Amplification depends on the ratio R7(4k7)/R3(22R). In short: increasing the value of R3 (22R) decreases the output voltage and vice versa.
Transistor: use BC549 and BC559
