This is one of the first radios with an integrated circuit. The circuit is from a Radio Electronics from November 1969. The circuit is powered by a 9 V battery.
This circuit appears in similar versions on this site. This is from a Popular Electronics from the 80's. The...
This two-transistor delay circuit from the 1960s was found in documentation from the time....
This circuit operates with signals from 150 kHz to 1 MHz and makes use of a known NAND CMOS gate....