This circuit was found in Mullard's transistor application manual from 1960. More modern transistors can be used. The zener diodes used have the indicated voltages.
This oscillator can use inverters or connected AND or NAND gates as such. The signal produced with...
This project, found in a 1981 documentation, consists of an interesting adaptation of the test...
This 1970 circuit triggers a load when it receives a signal. Components are common and SCR admits...