A three terminal high current A. C. switch

Silicon Controlled Rectifiers have proven to be excellent devices for the control of electric power. However, one shortcoming of these p-n-p-n power devices is their inability to conduct current bilaterally. Although two terminal devices have been described and fabricated which can be triggered into current conduction in either direction, they require either a very rapidly rising anode voltage or a voltage pulse which exceeds the avalanche breakdown voltage of the blocking junction to trigger. This paper describes a high current multiple junction device which can be triggered into conduction in either direction by the application of a low voltage, low current pulse between the trigger terminal and one of the load current terminals. Such a device is ideally suited for the switching and phase control of A.C. current.