Found in a 1949 Radio Electronics, this 4-tube circuit was fed directly from the mains with a half-wave rectifier.
The circuit presented is quite simple, employing tone modulation of the signal. To receive the...
This fast-acting circuit was found in the July 1969 Radio Electronics magazine. The trigger point...
This preamp was found in an old English publication. Any usage JFET can be employed. The output is high...