Found in a 1967 General Electric SCR manual, this circuit can be used to protect a load by switching in case of excess current. R1 determines the trigger current.
This TTL circuit has a well-known configuration, having been found in a Radio Electronics magazine...
Found in American documentation from 1968 this circuit is based on discrete components in addition...
The diagram shows an AND gate implemented with an LM3900 transconductance operational. The circuit is...