This circuit was obtained from an Electronics Design of 1964. The circuit makes use of tunnel diodes that are uncommon today. The circuit works with very weak signals.
This circuit was found in a 1967 Raytheon manual. The transistors are from the time. Equivalent modern...
This circuit was published in a 1979 magazine, but it can still be easily assembled as the...
The circuit presented generates short pulses. This configuration was found in a publication from...