This circuit was found in an old Poptronics. Operational amplifiers can be replaced with equivalents. The power supply must be symmetrical.
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...