Old superheterodyne (T1611E)

Found in a 1949 Radio Electronics, this commercial circuit was found in many countries, including Brazil.

20 V x 100 mA regulator using FET (CB8671E)
Found in an EEE this circuit uses FETs of the time and a bipolar one. Current equivalent...
Capacitive Switch (CB4994E)
This capacitive switch or approximation relay was found in a 1980s US publication. Power should...
Triggered Astable NOR Gate CMOS 2 (CB10729E)
Although it is a common configuration today, this circuit was taken from an old publication. The...