We found this circuit in an article in Radio Electronics magazine from November 1971. The circuit has several sensor inputs and is based on programmable unijunction transistors or PUTs.
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...