We still have the problem of zero voltage gaps to address. In fact, we end up with twice as many voltage peaks, and this is important, as you’ll see below. The result is a series of 12 volt peaks as shown at Point C of Figure 1. It actually transforms negative voltage into positive voltage. This diode bridge goes a bit further than the single diode present in a microwave oven, because it doesn’t merely eliminate negative aspects of alternating voltage. The wall wart’s diode bridge consists of four electronic components, namely the diodes, which are connected together. They require voltage that doesn’t alternate, and this is where the wall wart’s diode bridge and capacitor come into play.įigure 1 – The Workings of the Wall Wart Transformer The fact that the voltage being put out results in waves of energy which alternate between a positive maximum value, zero, and a negative maximum value, makes it an unacceptable power source for most electronic devices. These voltages are shown at Points A and B in Figure 1 below. We discovered how its transformer converts the 120 volts emanating from your average wall outlet to the 12 volts required by most electronic devices. Last week we began exploring the inner workings of the wall wart. The diode and capacitor within both the microwave and the wall wart are key to facilitating this magical act, but in the wall wart it happens at a much lower voltage, about 12 volts. If you will recall from our discussion of microwave ovens in the past few weeks, the transformer in a high voltage circuit transforms 120 volts into a much higher voltage, say 4000 volts, in order to make things work. Wall warts do much the same thing and in very much the same way. What do wall warts, aka AC wall adapters, and microwave ovens have in common? Well, in previous blogs discussing microwaves, we saw how a microwave oven’s high voltage circuitry uses a transformer, diode, and capacitor to effectively convert AC voltage into DC voltage.
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