Used in conjunction with the 590 Programmable controller.
Provides a momentary 12 volt DC pulse output when a steady 5 to 12 volt DC input is applied.
By plugging a 781C power supply into a switched AC outlet on the back of an AM/FM receiver, a low voltage, switched DC signal is made available to the 590.
This could be used to trigger a power-on command for a common source component, for instance.