Audio Kits
Microphone amplifier with low noise
This low noise microphone amplifier is build with MAT02 produced by PMI. This mic amplifier is very performant and has a very low noise level. The amplification can be 20dB or 23.5dB (10x or 15x ) selected by S1.
The output impedance is 70 Ω at 23.5 dB gain and with R3 = 220KΩ the input [...]
Mini audio compressor schematic
This mini audio compressor circuit use only one active component T1. The audio signal goes thru C1, R1, D1, C2, R3. Still a part of audio signal charge the D3/D4 detector and creates a control voltage for T1.
The fading time depends on C4 and R5. With an audio input variation of 50dB, the output signal [...]
Simple mixer circuit schematic - Common base
The mixer schematic is build on common base principle, where input voltages are transformed in alternative currents wich are summed to form the alternative current component for the collector. The total amplification is R6 / Ri, where Ri is one of the input resistors. I’ve build this mixer for a little transmitter and works great.
