A trigger transformer is a small, usually ferrite cored

transformer In electrical engineering, a transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple Electrical network, circuits. A varying current in any coil of the transformer produces ...

autotransformer In electrical engineering, an autotransformer is an electrical transformer with only one winding. The " auto" (Greek for "self") prefix refers to the single coil acting alone. In an autotransformer, portions of the same winding act as both the p ...

used in applications requiring a high voltage pulse, typically to start

ionization Ionization or ionisation is the process by which an atom or a molecule acquires a negative or positive Electric charge, charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged at ...

of a gas to allow a current to pass.Amglo Kemlite Laboratories
/ref>

Uses

Trigger transformer cores may be utilized in a unipolar ( electromagnetic flux strictly positive or negative) or bipolar (swinging between positive and negative) manner. Applications also differ in whether or not they saturate the core (termed a saturating trigger transformer).

Strobe light A strobe light or stroboscopic lamp, commonly called a strobe, is a device used to produce regular flashes of light. It is one of a number of devices that can be used as a stroboscope. The word originated from the Ancient Greek ('), meaning ...

s, for instance operate the core in a unipolar, unsaturated mode.

Capacitor In electrical engineering, a capacitor is a device that stores electrical energy by accumulating electric charges on two closely spaced surfaces that are insulated from each other. The capacitor was originally known as the condenser, a term st ...

s are charged to approx. 300 volts, at which point a second capacitor pulses voltage through the transformer, achieving the approx. 2000-6000 volts (depending upon the characteristics of the specific flash tube) necessary to overcome the resistance of the inert gas (such as

xenon Xenon is a chemical element; it has symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...

) between the electrodes, ionizing it. Trigger transformers operate by means of a secondary coil with hundreds, even thousands, of turns of very fine copper wire, trading current for voltage. Much like in

lightning Lightning is a natural phenomenon consisting of electrostatic discharges occurring through the atmosphere between two electrically charged regions. One or both regions are within the atmosphere, with the second region sometimes occurring on ...

, this plasma has much lower resistance, and the capacitor can discharge rapidly across it. The capacitors begin charging again, starting the cycle anew and giving rise to their characteristic periodic flashing. Capacitors alone would result in a continuous arc. Having achieved the voltage necessary to cause

dielectric breakdown In electronics, electrical breakdown or dielectric breakdown is a process that occurs when an electrically insulating material (a dielectric), subjected to a high enough voltage, suddenly becomes a conductor and current flows through it. All ...

, they would maintain it indefinitely. So-called saturating trigger transformers find use in circuits that intentionally utilize core saturation and/or operate in a bipolar fashion, such as DC-to- AC power inverters. Trigger Transformer Theory - Gowanda Electronics
/ref> Inductors are also commonly used in place of a trigger transformer, however are not considered transformers themselves, although similar in operation.

References

Electric transformers {{electronics-stub