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Types of Single Output DC Power Supplies

A direct current power supply is an electrical device the produces a DC voltage. Many universities and laboratories use power supplies that convert the high voltage alternating current available from the electric company into a wide variety of DC voltages. These machines are simply complex and elaborate versions of the basic single output DC power supply.

Common Parts
- A simple single-output DC power supply is made out of a transformer, a rectifier, a filter capacitor, a limiting resister and a bleeder resister. The transformer changes the AC voltage that the power supply receives from the wall outlet to a lower AC voltage. The rectifier changes it to a DC voltage. The limiting resistor prevents power surges from damaging the capacitor. The capacitor itself filters out unwanted voltages. The bleeder resister discharges the capacitor when it's not in use.
Uncommon Parts
- Power supplies connected to power sources prone to sharp voltage spikes are vulnerable to damage. Such power supplies also have voltage regulators built in, to smooth out the voltage and eliminate sharp spikes. These voltage regulators often use diodes and/or other semiconductor components. DC power supplies subject to high voltages or at risk of circuit failure that causes high voltages also include a fuse. At dangerously high voltages, the fuse melts, protecting the more delicate components.
Types
- There are two types of single-output DC power supplies: low-voltage and high-voltage. Low voltage supplies use relatively few parts; you can build one easily and safely on a blank circuit board with spare parts. A high voltage power supply uses more and rarer components that can handle high loads of power; it also is enclosed in either a nonconducting box or a grounded metal box.
The Adapter
- Basic single-output DC power supplies are readily available and found in many homes. Sold under the name "adapters," they consist of a small plastic box with a wire attached. The box plugs into a wall outlet and the end of the wire plugs into the device needing a DC voltage.
Other Uses of the Term
- Technically speaking, batteries and DC generators are types of DC power supplies. Batteries supply DC power from chemical reactions taking place inside them. Generators transform other types of power, such as wind or burning fuel, into DC electric power. These devices are not commonly referred to by the term "DC power supply."

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