Two-transistor voltmeter (CB21665E)

This circuit was taken from Popular Electronics from May 1968. The circuit is sensitive with various scales and the transistors are from the period.

Component Tester (CB4313E)
This circuit consists of a simple continuity test with two transistors forming a relaxation...
100 W Inverter (2) (CB13974E)
This circuit is a manual of 1972 RCA power transistors. The critical components of the project are...
High speed trigger (CB21850E)
Found in the 1974 Ferranti transistor manual, this Schmitt trigger circuit uses general-purpose transistors...