This 40-second delay switch was found in a 1965 Electronic Design. The unijunction transistor might be the 2N2646 and the SCR a sensitive modern equivalent.
This portable transceiver circuit for the 11 meter or 27 MHz band was found in a 1991...
This circuit was found in an American 1980s documentation. It makes use of an unusual MOSFET today...
This circuit was found in an old Linear Technology documentation. The working principle can be...