This flip-flop circuit with general purpose transistors was found in American documentation from the 1980s. The maximum operating speed depends on the transistors. Diodes are commonly used.
This configuration is from a 1987 publication, but it can be easily assembled today, as the...
This is a simple source indicated for powering low voltage projects on the bench. The circuit is...
This circuit is from Philips' 70s documentation. Transistors can be replaced by modern...