Power Supplies: Turning Wall Power into Usable Power

By Cliff Potts, CSO, and Editor-in-Chief of WPS News

Baybay City, Leyte, Philippines — August 28, 2026 — 12:30 p.m.

Throughout this series we have examined individual electronic components.

Resistors limit current.

Capacitors store energy.

Batteries provide portable electrical power.

Relays control larger circuits.

Transformers change voltage.

Now it is time to put many of those pieces together.

The result is called a power supply.

Almost every electronic device ever built has one.

Without a power supply, even the most sophisticated computer, radio, television, or communications system becomes an expensive collection of parts.

The job of a power supply sounds simple.

Take electricity from one source.

Convert it into the form the equipment actually needs.

In reality, that simple description hides some elegant engineering.

Most homes receive alternating current, or AC, from the electrical grid.

Many electronic circuits, however, require direct current, or DC.

That means something must convert one into the other.

The transformer is usually the first step.

As we learned last week, the transformer can safely increase or decrease voltage while providing electrical isolation.

A household outlet may provide 120 or 240 volts AC, depending upon where you live.

The electronic circuit inside a radio may require only twelve volts.

A transformer performs the first part of that job.

The next step belongs to the rectifier.

A rectifier allows electricity to flow in only one direction.

Early electronic equipment often used vacuum-tube rectifiers for this purpose.

Later designs replaced them with semiconductor diodes.

Regardless of the technology, the goal remained the same.

Convert alternating current into direct current.

The result, however, is not perfectly smooth.

Instead, the voltage resembles a series of hills and valleys.

That is where another familiar component enters the story.

The capacitor.

Remember our discussion about capacitors acting like buckets of electricity?

Inside a power supply, capacitors fill in those valleys.

They store energy when the voltage rises.

They release that stored energy as the voltage falls.

The result is a much smoother DC output.

One simple component performs a remarkably important task.

Many modern power supplies go one step further.

They regulate the output voltage.

Whether the incoming power fluctuates slightly or the electrical load changes, the regulator attempts to keep the output steady.

Stable voltage means stable electronics.

Computers appreciate stable voltage.

Radios appreciate stable voltage.

Nearly every electronic circuit performs better when supplied with clean, consistent power.

Electronic Archaeology Note

One of the things that fascinated me when I first studied electronics was discovering that a power supply was not just a transformer.

It was an entire system.

Each component performed one specific job.

The transformer changed the voltage.

The rectifier changed AC into DC.

The capacitors smoothed the output.

The regulator maintained stability.

Separately, they seemed simple.

Together, they quietly powered nearly every electronic device I ever worked with.

That realization changed the way I looked at electronics.

Instead of isolated components, I began seeing complete systems.

Power supplies have evolved dramatically over the decades.

Older equipment often contained large, heavy transformers operating directly from household line frequency.

You could feel their weight the moment you picked up the equipment.

Modern switching power supplies operate at much higher frequencies.

Their transformers are dramatically smaller.

They are lighter.

More efficient.

Often far more complicated.

Despite the differences, both designs accomplish the same basic objective.

Deliver the correct power safely and reliably.

Power supplies also remind us that electronic equipment is only as good as the electricity feeding it.

Poor power causes strange problems.

Voltage spikes can damage components.

Voltage drops can cause unpredictable behavior.

Electrical noise can interfere with sensitive circuits.

Good power supplies exist to protect equipment from many of these problems while delivering the electricity the circuit actually needs.

That is why engineers devote so much attention to power supply design.

If the power is unstable, everything connected to it may become unstable as well.

Electronic Archaeology is about understanding how the pieces fit together.

The power supply is one of the first examples where we can finally see multiple lessons working together.

Electricity.

Magnetism.

Induction.

Transformers.

Diodes.

Capacitors.

Regulation.

Each lesson has been preparing us for this point.

The individual components no longer stand alone.

They become a functioning machine.

That is how real electronics works.

Not as isolated parts.

But as complete systems.

Next week we will begin exploring one of the most important inventions in communications history.

The vacuum tube.

For nearly half a century, it amplified voices, transmitted radio signals, powered radar systems, and helped build the first electronic computers.

Electronic Archaeology is finally arriving where many of us first became fascinated with electronics.

If this work helps you understand what’s happening, help me keep it going: https://www.patreon.com/cw/WPSNews

For more from Cliff Potts, see https://cliffpotts.org

References

Horowitz, P., & Hill, W. (2015). The Art of Electronics (3rd ed.). Cambridge University Press.

Encyclopaedia Britannica. (2025). Power supply. Encyclopaedia Britannica. https://www.britannica.com/technology/power-supply

U.S. Department of Energy. (n.d.). Fundamentals Handbook: Electrical Science. U.S. Department of Energy.