We found this circuit that can reach 50 MHz in the February 1997 Electronics Now magazine. The integrated circuits used are not very common today.
This configuration, which requires a symmetrical power supply for the 741, can be implemented with other...
This timer with two unijunction transistors and one SCR was found in an American documentation from 1964....
This simple metronome, from 1985 documentation uses only transistors and has two settings. For...