This two-tube circuit, one being a double, was found in Radio Electronics magazine from July 1958. The distance to the microphone depends on noise and losses. The cable must be shielded.
The circuit shown was found in an American documentation from 1964. The circuit uses transistors of...
We found this antenna amplifier or Booster circuit in an Electronics Now from the 90s. The circuit...
This dimmer with a unijunction transistor and SCR appeared in Radio Electronics magazine in March...