What is a Power Supply?
A power supply is a type of device that supplies the electricity, or power, to an electrical load. The term power supply generally refers to devices that convert one type of electrical energy to another, but there are other types as well. Regulated power supplies are able to control output voltage or current at a specific value, and they can actually hold this value even when there are variations in load current or voltage from the energy source used by the power supply.
In order to work and to provide power to the electrical load, the power supply needs to have energy. The source of the energy can differ depending on the sort of power supply used. They can get their energy in a number of different ways. Some of the most common include electrical energy transmission systems, generators and alternators, solar power, fuel cells, and batteries.
How Does a Power Supply Work?
Power supplies are one of the most important elements for electronic devices today. Without the power supply, the device would simply not be able to function. However, most people do not stop to consider how the power supplies actually work and what they do to allow all of those gadgets and devices around the house and office to work. Consider just a few of the many items that have power supplies, including your phone’s charger, computer, video game consoles, alarm clocks, and nearly every other electrical item you have.
Quite often, the power supplies are actually within the unit, so you do not see them. Other times, as with chargers, they are visible. A good example of this would be the latest videogame consoles, the PS4 and the Xbox One. The PS4 has an integrated power supply, while the Xbox features an external power supply.
The power supplies will take energy and convert it for use with the device. It is important to remember that different types of devices need to have differing amounts of electrical energy to function, and the power supply needs to be able to convert just the right amount of power for the unit to work properly. This is why manufacturers always insist you only use the right type of power supply with their devices. If the power supply is flooding the unit, no matter what it might be, with too much power, it could damage it severely. The best power supplies also strive to provide the right amount of electrical energy at the lowest cost possible.
Power supplies have a number of functions they have to perform, the first being turning AC voltage into DC voltage at the appropriate levels. They also need to filter the power to make sure the voltage is smooth and will provide the constant voltage the device needs. As mentioned, they also need to protect the device by providing only the right amount of power.
What Types of Power Supplies Exist?
- Bench Power Supplies – These power supplies allow the user to have a substantial amount of control. They are in a case and they feature controls that let the user change and alter the operating characteristics so they can fit particular applications and devices. These are actually very popular in laboratories because it gives one better control. However, it is possible to use them in other areas as well. They have displays that can show a number of things depending on the unit. The bench power supplies will typically show the current and voltage and have knobs and dials that allow you to adjust them. Usually, these are AC inputs.
- Computer Power Supply – Without the computer power supply, your computer will not do anything at all. The power supply attaches to the computer, takes the AC power coming into your home, and then converts it to DC power that your computer can then use. Many refer to these sorts of power supplies as switching supplies, as they switch the AC power to DC power. Different types of power supplies are available for different types of computers. Laptops and notebooks, for example, will generally have an external power supply. Desktops are different, as you will see.
- Desktop Power Supply – The desktop power supply is actually a part of your desktop computer. The power supply is a metal box that actually sits inside of the computer. This is where you plug the computer into the wall with a cord. Because there are so many different types of computers, and they have different power needs, there are different size power supplies. When the power supply unit goes bad and stops working on a computer, it is possible to change it out. However, it is always very important to make sure you are using the right supply for the desktop.
- DIN Rail and Panel Mount Power Supplies – These sorts of power supplies are actually mounted onto either rails or the sides of devices. The DIN rail is common for mounting circuit breakers, power supplies, and more in equipment racks. They are actually standard in many types of equipment, and specialized power supplies will mount neatly along the side of the rail. The panel mount power supplies affix to panels and device walls.
- Embedded Linear Power Supplies – A linear power supply is one that offers smooth and constant voltage that has been set to a specific value. They feature regulators that help to reduce the noise and ripple effect in the current. Embedded power supplies are actually right in the electrical devices to which they provide power.
- Embedded Switch Mode Power Supplies (SMPS) – A large number of electronic devices today make use of these embedded SMPS to power the circuitry. Many find this advantageous to using linear power supplies because of their efficiency. They are also lightweight and have the ability to generate less heat because of their efficiency. A number of different types of SMPS are out there today, including voltage converters, inverters, rectifiers, and cycloconverters. Rectifiers are AC in and DC out, voltage converters are DC in and DC out, inverters are DC in and AC out, and cycloconverters are AC in and AC out.
- Plug-In Power Supply – The plug-in supplies are some of the most common types of power supplies you will find today. The power supply has a plug that connects to the wall outlet or a surge protector. You connect the power supply directly to your various devices for powering the device or for charging it. One of the drawbacks to these types of units is that they will constantly use standby power. This means that even when you are not using them, they are draining electricity, causing the power bill to rise. It is best to unplug them when not in use, or to connect them to a power strip so you can turn it off. These have a number of benefits. They are safe, lightweight, easy to replace, and very versatile. In addition, they remove the power supply from the device itself, which helps to reduce the amount of heat the device has to endure.
- Rack Mount Power Supplies – A rack system features room for a number of power supplies, which might be necessary for servers. These power supplies are able to offer uninterrupted power and redundant power to the servers, so they can handle greater workload challenges. High quality power supplies will feature fast and efficient switching technology that features filters to help smooth out the voltage. These are essential for many communications operations today. The power supplies available today come in many configurations with various inputs, handles, colors, and indicators, so most can find a supply unit that will meet their needs.
What are AC and DC?
AC and DC are the two types of currents we use in our daily lives to provide power to all of the electrical devices we need. AC stands for alternating current, while DC stands for direct current. When people first began to understand and harness currents, they had differing opinions on which one would be the best solution. Thomas Edison was a proponent of DC current, while George Westinghouse and Nikola Tesla were proponents of AC current. While we utilize both currents for different things today, most consider Westinghouse to be the “winner” of the war of the currents.
Part of Edison’s plan to win was actually his publicity campaign that attempted to show people the dangers of using AC. His team spread disinformation about the dangers of AC. He had animals electrocuted using AC power, in public so people could see. He even went so far as to try to make the term “Westinghoused” synonymous with electrocution.
Alternating current is the power that comes from a power plant, and is the type of power that runs through the walls of your home. This power will reverse at a rate of 60 times per second in the United States and 50 times per second elsewhere. The fact that the current reverses is where it gets the name “alternating” current. Since the devices we use need to have DC current, the power supplies in those devices transform it.
Direct current always flows in the same direction. It does not alternate or reverse. The best examples of devices that offer DC current today are fuel cells, solar cells, and batteries.
Alternating current does have some advantages though. It is easier to change the voltage of the power with the use of transformers. This allows power companies to save money, while still being able to transport the power over vast distances.
What is the Difference Between an AC and a DC Power Supply?
An AC power supply is a device or component that will transfer the alternating current to an electrical device. These sorts of power supplies will generally plug into the wall socket, where they will then convert the AC power to DC power, which the device will need.
A DC power supply is somewhat different, although the goal is the same. They still want to take the AC power and turn it into DC power. These sorts of power supplies make use of rectifiers, filters, and regulators. These three components help to provide the smooth power needed for the operation of electronics.
For some devices and machines, running on direct current alone, via batteries and the like, is generally not possible because DC does not offer enough voltage. DC is lower voltage than AC. They need to have more power, and they may run on AC rather than DC power. These offer higher voltages, but they are not right for all devices. It is important to follow the guidelines from manufacturers when making use of any type of power supply.
For most items though, DC power is the top choice. The power supplies that convert the AC to DC are able to provide more than enough power. The adapters and power supplies regulate the amount of voltage that goes into the device so they do not overload, which could potentially fry the electronics.
What Are the Characteristics of a DC Power Supply?
A DC power supply, as mentioned, needs to have a rectifier, filter, and regulator. The goal of the rectifier is to convert the AC to DC. The addition of the filter removes the pulse in the current that occurs with AC. The regulator then provides the stability and control to ensure the current stays at a certain level. Sometimes, they will also have a capacitor in them. The capacitor aids the regulator and helps to control and remove electrical noise. This can supply a clean and smooth source of power.
Even with the elements designed to remove the ripple effect, some will remain. This could cause issues with some devices, but for charging batteries and the like, the ripple is not a problem. This is because they do not need to have a constant and steady stream when simply charging.