This is the circuit diagram of low impedance microphone amplifier. The circuit designed for use with low impedance (~200 ohm) microphones. It will work with regulated voltages between 6-30VDC. If you don’t build the impedance adapter part with T1, you get a microphone amplifier circuit for higher impedance microphones. In this case, you should directly connect the input signal to C7 (bypass the TI transistor).
Low Impedance Microphone Amplifier Component list:
| R1=15k | C1= 3k9 | U1= TL081 | ||
| R2= 150k | C2= 100u | D1= 1N4148 | ||
| R3= 2k2 | C3= 22u | CN1= SIL6 | ||
| R4= 820 | C4= 4u7 | |||
| R6= 10k | C5= 470u | |||
| R7= 10k | C6= 10u | |||
| P1= 1M | C7= 100n | |||
| C8= 47u UNIPOLAR |
PCB layout (bottom):
PCB layout (top-component placement):
Good luck with this low impedance microphone amplifier circuit project 🙂