This circuit is from a Radio Electronics from December 1964. The components are from the time and modern equivalents for transistors and diodes can be used.
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...