Power Supply Repair

What is an electrical power supply?

An electrical power supply is a device or system that converts electrical energy from a source, such as a battery or utility grid, into electrical energy that can be used by devices or systems. Power supplies can come in a variety of forms, such as AC-DC or DC-DC converters, and can be used to provide power to devices such as computers, appliances, and industrial equipment.

A power supply is an electrical device that supplies electric power to an electrical load, sometimes referred to as an electric power converter. Its main purpose is to convert electric current from a source to the correct voltage, current, and frequency to power the load. Power supplies can be standalone pieces of equipment or built into the load appliances they power, such as those found in desktop computers and consumer electronics devices.

In addition to converting electric current, power supplies may perform other functions such as limiting the current drawn by the load to safe levels, shutting off the current in the event of an electrical fault, power conditioning to prevent electronic noise or voltage surges on the input from reaching the load, power-factor correction, and storing energy to continue powering the load during a temporary interruption in the source power (uninterruptible power supply).

All power supplies have a power input connection that receives energy in the form of electric current from a source, such as the electric power grid, energy storage devices like batteries or fuel cells, generators or alternators, solar power converters, or another power supply. They also have one or more power output or rail connections that deliver current to the load. These connections are usually hardwired circuit connections, although some power supplies may use wireless energy transfer to power their loads without wired connections.

DC Power Supplies

The AC-to-DC power supply is designed to operate on an AC input voltage and produce a DC output voltage. The amount of AC frequency components present in the output voltage, also known as ripple voltage, depends on the power supply's operation and the frequency of the AC input voltage. This ripple voltage may be significant or insignificant depending on the specific requirements of the application.

On the other hand, a DC-to-DC converter is a power supply that operates on a DC input voltage. However, this section will primarily focus on the AC-to-DC variant.

AC Power Supplies

An AC power supply typically receives voltage from a wall outlet or mains supply and then employs a transformer to step up or step down the voltage to achieve the desired voltage level, while also providing some filtering. If the input voltage and output voltage are the same, the transformer is referred to as an isolation transformer. If the transformer does not offer mains isolation, it is referred to as an autotransformer and a variac refers to a variable output autotransformer. Some AC power supplies are designed to maintain a nearly constant current, with the output voltage varying based on the load impedance.

Some AC power conversion methods do not require a transformer. If the device's primary function is to filter AC power and the output voltage and input voltage are the same, it may be called a line conditioner. In contrast, if the device is designed to offer backup power, it may be referred to as an uninterruptible power supply. In the past, vacuum tube AC/DC receivers utilized a voltage multiplier topology to directly step up AC power.