Power Supply Circuits


Linear power supplies work by getting the 127 V or 220 V from the power grid and lowering it to a lower value (e.g. 12 V) using a transformer. This lower voltage is still AC. Then rectification is done by a set of diodes, transforming this AC voltage into pulsating voltage. The next step is filtering, which is done by an electrolytic capacitor, transforming this pulsating voltage into almost DC.On high-frequency switching power supplies, the input voltage has its frequency increased before going into the transformer (10-20 KHz are typical values). A power supply of good quality and with enough capacity can increase the durability of your equipment. Just to have an idea, a high-quality power supply will cost less than 5% of the PC total amount. On the other hand, a low-quality power supply can cause several intermittent problems, which are mostly difficult to be solved.Although linear power supplies work very well for several low-power applications – cordless phones and video games consoles are two applications that come in mind –, when high power is needed, linear power supplies can be literally very big for the task.

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