Erie Institute of Technology

News and Events

Understanding AC and DC Power Supply

Dec 7, 2022 | News

No, this isn’t a blog about an early 80s rock band. But you might be thunderstruck to learn the differences between AC and DC power supplies. Take a few minutes to learn more about it and where you can get proper training and education about electrical systems.

What Is a Power Supply

A power supply is a device that converts the electrical energy coming from a power source into the voltage and current values powering a load. In other words, the power supply ensures that electrical power is supplied in a controlled manner. A power supply can control and accurately adjust the voltage to several loads—sometimes simultaneously—without allowing changes in input voltage or other connected devices to affect the output.

Difference Between AC and DC Power Supply

Alternating current (AC) power supply refers to electric charges that change direction periodically. The voltage in AC circuits also regularly reverses due to current direction changes. AC power supply is typically used to power office buildings, homes, and more.

On the other hand, direct current (DC) power supplies provide a constant voltage or current. The current from a DC power supply only flows in one direction. This type of power supply is typically used for small electronics and devices that use a battery.

Become a Skilled Electronics Technician

Open the door to a rewarding career!

Linear vs. Switching AC/DC Power Supply

Linear AC/DC Power Supply

  • Linear AC/DC power supplies use a simple design. The AC input voltage can be reduced to a suitable value for the intended application by using a transformer. With the voltage reduced, it’s then rectified and turned into DC voltage. From there, it’s filtered to further improve the waveform quality.
  • One hindrance of the linear AC/DC power supply is the transformer’s size. Since the input voltage is transformed at the input, the transformer would need to be large and heavy. Large inductance values are necessary to transfer high amounts of power from the primary to the secondary coil at low frequencies. This makes it nearly impossible to make miniature power supplies.
  • To maintain a consistent voltage at the output, a linear AC/DC power supply uses linear regulators. Any extra energy will be dissipated in the form of heat by the linear regulators. At high power, the regulator would need to dissipate a lot of heat to maintain a constant output voltage. It would need an extremely large heatsink.

Switching AC/DC Power Supply

  • Modern semiconductor technology can handle power supply switching on and off quickly and efficiently—even when large voltages and currents are present. A switching AC/DC power supply allows for the elimination of dissipating excess power since it works more efficiently.
  • AC/DC power supplies use converters called switched-mode power supplies. These use a complex method for converting AC to DC power. In switching AC power supplies, there’s no need to reduce input voltage—it’s rectified and filtered in the input. The DC voltage travels through a chopper, where it converts the voltage into a high-frequency pulse train. After that, the wave will go through another rectifier and filter, which converts it back to DC and eliminates the remaining AC component.

Enroll in the Electronics Technician Program at Erie Institute of Technology

Ready to put your new knowledge and understanding of AC and DC power supplies to good use? Start by learning more about the electronics program at Erie Institute of Technology (EIT).

We offer training and education in the Medical Equipment Technician Program and Electronics Technician Program that’ll prepare you for a fulfilling career. We’ll even help you navigate the field with our job placement services upon completion. Get started today.


Ross Aresco


Ross Aresco is the CFO of Erie Institute of Technology. Erie Institute of Technology (EIT) is an Erie Pennsylvania technical/trade school providing training programs for medical, computer, electronics, manufacturing, and technology careers. EIT offers programs in many different areas to suit your interests and talents.

Share This