Different lamps require specialized ballasts designed to maintain the specific voltage and current levels needed for varying tube designs.įluorescent lamps come in all shapes and sizes, but they all work on the same basic principle: An electric current stimulates mercury atoms, which causes them to release ultraviolet photons. Since they use a higher cycle rate, you don't generally notice a flicker or humming noise coming from an electronic ballast. Modern ballast designs use advanced electronics to more precisely regulate the current flowing through the electrical circuit. This is the source of the audible humming sound people associate with fluorescent lamps. Magnetic ballasts may also vibrate at a low frequency.
Magnetic ballasts modulate electrical current at a relatively low cycle rate, which can cause a noticeable flicker. Check out this site for more information on this process. But the alternating current powering a fluorescent light is constantly reversing itself, so the ballast only has to inhibit increasing current in a particular direction for a short amount of time. The transformer elements in a magnetic ballast use this principle to regulate the current in a fluorescent lamp.Ī ballast can only slow down changes in current - it can't stop them. In short, a coiled length of wire in a circuit (an inductor) opposes change in the current flowing through it (see How Inductors Work for details). Increasing the current in the loop increases the magnetic field, which applies a voltage opposite the flow of current in the wire. This sort of field affects not only objects around the loop, but also the loop itself.
Positioning the wire in concentric loops amplifies this field. If you've read How Electromagnets Work, you know that when you send electrical current through a wire, it generates a magnetic field. A basic inductor consists of a coil of wire in a circuit, which may be wound around a piece of metal. The simplest sort of ballast, generally referred to as a magnetic ballast, works something like an inductor.
A fluorescent lamp's ballast works to control this.
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