With this 1-transistor circuit we have a high input impedance and good gain. The circuit is from a 1985 publication and the transistor can be any general purpose NPN like the BC548. The circuit operates with audio signals up to a few megahertz.

With this 1-transistor circuit we have a high input impedance and good gain. The circuit is from a 1985 publication and the transistor can be any general purpose NPN like the BC548. The circuit operates with audio signals up to a few megahertz.