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 is an old test circuit for integrated TTL counters, feeding a Nixie tube, common at the time....
I found this circuit in an Electronics Handbook from 1989. The circuit can be assembled with a...
This circuit makes use of a 2N301 germanium power transistor. We found it in a documentation from...