Flyback chronographs have a timing hand that can be rapidly reset, or "flyback", to zero. Flyback converter's transformer works differently, like an inductor. This requires a high power flyback transformer, and a high powered tube or transistor. It features common-cathode flyback diodes for switching inductive loads. A diode used in this way is called a freewheeling diode or flyback diode. Accordingly, flyback converter's transformer air gap has two functions. Basic topologies are resonant flyback and resonant half bridge. The flyback converter is an isolated power converter. A flyback converter is a power supply circuit operating on similar principles. In Figure 2, a flyback diode was added in antiparallel with the solenoid. This phenomenon is called flyback voltage. The common sources of the high voltage are ZVS flyback HV sources and neon-sign transformers. Few packages, like L9110, have built-in flyback diodes for back EMF protection. It is often confused with the flyback chronograph.