What distinguishes a trigger transformer from other types of electronic transformers? Basically, it is application! As the word “trigger” implies, a trigger transformer is used in a circuit that initiates some sort of action or event. Once initiated, some applications may no longer require continued presence of a voltage to complete the action or event. Other applications may need the voltage but for a limited amount of time. Regardless, the application provides a voltage pulse to the trigger transformer’s primary. The trigger transformer’s turns ratio steps up or steps down the secondary voltage as needed. The trigger transformer’s secondary then supplies voltage or current to its load. The load is usually the gate of a semiconductor switch such as a transistor, F.E.T., S.C.R., etc.. The trigger transformer also provides voltage isolation between the primary side circuit and the secondary side circuit. Most circuit designers would refer to the trigger transformer as a type of pulse transformer.