This circuit uses common components at the time of its publication in the 1980s. The circuit can be made with modern equivalent transistors. The input signal is sinusoidal.
This circuit is from 1977 documentation, but can be assembled with BC548 for Q1, Q2 and Q4, BC558...
Found in American documentation from the 90s, this circuit uses components that are still common...
This high impedance input amplifier is suitable for the use with piezoelectric sources such as...