I found this circuit in a documentation for radio amateurs from 1975. The FET could be the BF245. The circuit works in the range of 40, 80 and 160 meters of radio amateurs.
This watch was found in 2001 documentation. The watch is powered by 4 batteries. To save energy, the...
This circuit is from Motorola's Linear Databook from 1990. The integrated circuit and transistors are...
This is one of many possible touch switch configurations using CMOS integrated circuits. The...