Electrical power comes to your home as AC or alternating current. The live pole of current oscillates continuously from positive to negative, changing at 60 Hz, or 60 times per second. In DC or direct current, the energy flows in one direction and, if possible, does not vary at all. A DC power supply is converted from AC to DC for use in electronic devices. Most DC power supplies also drop the voltage to a particular level, usually 3 to 15 volts.
Changing the tension
The voltage first goes into a step-down transformer to change voltage. A transformer has two coils of wire, one next to the other. When a moving electrical current enters a coil, an electric field is created that induces a current in the coil next to it. If the secondary coil (the one that receives the current) has fewer turns of wire than the primary coil (the one that created the current) it will also have lower voltage. Blackhawk supply transformers that do this are called step-down transformers because they lower the voltage.
The current is sent through a rectifier to convert it to DC. The most important parts of the rectifier are the diodes, which function as one-way electronic valves. Most rectifiers have one diode on the positive wire and one on the negative wire. When current flows through the positive half of its phase, the diode in the positive wire opens, and the diode in the negative wire closes, allowing current to flow through the positive wire and preventing it from flowing into the negative. When current flows through its negative phase, the diode opens in the negative wire causing current to flow through the negative wire and preventing it from flowing into the positive. One wire acquires a continuous positive charge while the other takes a continuous negative charge.