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.
The diagram, obtained in an old European documentation, shows the ways to trigger and to shut down...
In the figure we have a three-phase AC motor control for voltages up to 600 V or 1200 V depending on...
This shield circuit can serve as a basis for a digital mixer or simply for a switch without noise...