In this circuit we have the way to use two transistors as a regenerative pair simulating an SCR. The circuit is from a 1965 General Electric documentation.
Using components from the era, this 90's EDN circuit is used in analog to digital conversion...
Found in an American publication from the 90s, this circuit allows the supply of 3, 6 and 9 V...
We found this circuit in an old Popular Electronics. The circuit is experimental, driving an LED...