This old 1967 audio preamp uses germanium transistors. It was found in Japanese documentation at the time and has a gain of 70 dB, being powered by p V. The input sensitivity is only 12 mV.
Based on common components, this circuit was found in an English publication. The circuit is...
This circuit is from Mullard 1969 documentation. The circuit operates at a relatively high supply...
In relation to the previous circuit (CB18493E) this spy has an extra transistor, which can be a...