Found in an old Radio Electronics, this circuit uses common components today. The resistors of the IC output determine the stair steps.
This circuit is suitable for low impedance m icrophones. Gain is given by the 2M2 resistor. This...
This sensitive circuit was found in old documentation. The SCR can be any of the 106 series and...
This preamp with several inputs using germanium transistors from the time was found in Japanese...