This sensitive touch key appears on this website from other sources. This version was taken from a 90s American documentation. The source must not be of transformerless type.
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...