Two-stage single-supply audio preamplifier for a microcontroller ADC (e.g. Teensy A2).
- 5 V supply with mid-rail bias (~2.5 V)
- AC-coupled input (jack / line / mic level)
- Non-inverting gain stage with 100 kΩ pot + 2.2 kΩ (hardware gain)
- Unity-gain buffer with bias on the non-inverting input
- Output AC-coupled into a 10 kΩ / 10 kΩ divider for the ADC pin
Simulate with a ~100 mV, 1 kHz sine source. Quiescent: OA1/OA2 outputs sit near 2.5 V; A2 node shows the attenuated AC signal. Adjust RV1 to change amplitude.
I'm not an engineer, comments are welcome.
