This transistor gain test was published in Radio Electronics magazine in July 1959. The transformer used is a special type common at the time. The circuit tests general-purpose transistors.
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...