This circuit was found in an article in Electronics Now magazine from March 1997. The transistors are general purpose, and the indicator is a 1 mA full scale analog type.
Quadrature Generator for Transistor and SCR Testing This circuit was found in US 1980s...
This circuit, with output currents up to 500 mA, can stabilize or regulate the output voltage of a...
This circuit that uses only transistors that are still common was found in a 1995 documentation. The TIP41...