This is a transistor flip-flop suggested by General Electric in a 1966 paper. The transistors are of the time and can be used equivalents.
The 556 consists of a double integrated circuit 555, which can be replaced by them in this...
This circuit is from an old operational amplifiers manual. However, the setting applies to modern...
This circuit is from a 1988 documentation, but uses components quite common today. The circuit...