This circuit for the very low frequency range was found in the Radio Electronics magazine of February 1983. The components are according to the frequency range to be amplified.
We found this circuit in a Mullard manual from 1960. The transistor is a phototransistor of the...
The circuit that gave rise to this configuration was found in a magazine of the 1980s with the...
This oscillator with FET was found in Popular Electronics from the 90s. This traditional...