Audio Amplifiers
Miniature audio amplifier
This miniature audio amplifier delivers up to 250mW and can be used like a final stage audio amplifier for radio sets. The schematic is very simple: one BC547 transistor controls a balanced power amplifier built with BC337 and BC327. The total amplification is around 15x and is determined by R1, R3 and P1. The input [...]
Dynamic microphone amplifier - low noise
This dynamic microphone amplifier circuit has a total gain of 200 times. If we use 200Ω microphones R4 must be 220Ω and C1 is 4.7uF. If you want the to get the lowest noise signal from this dynamic mic amplifier use metalic resistors for R3 .. R6 and for C1 use more MKM capacitor in [...]
Electret microphone amplifier circuit
This article describes an compact electret microphone amplifier but you can connect dynamic microphones with low resistance. Electret microphones can be inserted in the same box with the amplifier, it only need 5 to 10V or 9V battery with a current consumption of just 1.5mA.
Here you got the electret amplifier schematic:
