In the figure we have the way to obtain the Exclusive-OR function with 1 transistor. The circuit is from a 1964 Electronic Design. The transistor can be any general purpose PNP.
The circuit shown is from an old European publication. In it we have the way to activate a relay...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
This circuit was found in an American documentation and can be added to common amplifiers of any...