History's Greatest Electrical Innovations You've Never Heard Of


Electricity is something most of us take for granted in our daily lives. We flip a switch and a light turns on, or plug in our phones and they begin to charge. But behind these simple actions are decades, even centuries, of innovation by pioneering scientists, engineers and inventors.

In this article, I will highlight some of the most important yet relatively unknown electrical innovations that have shaped the modern world. These are the unsung heroes of electrical engineering - breakthroughs and inventions that transformed technology yet remain obscure to the general public. By exploring this fascinating niche of technological history, we can develop a deeper appreciation for the invisible forces that power our lives.

The Self-Starting Synchronous Motor

In the late 19th century, the invention of the induction motor enabled the widespread adoption of alternating current for power distribution. However, induction motors had limitations. They could not easily adjust their speed in response to changes in load. This is where the synchronous motor, invented by Charles S. Bradley in 1889, changed the game.

What made Bradley's motor special was that it was self-starting. Earlier synchronous motors required an external power source to get their rotors spinning. Bradley's innovative winding design allowed the rotor to begin rotating on its own through induction when powered up. This made synchronous motors far more practical and paved the way for their use in industrial applications.

The self-starting synchronous motor allowed for precise speed control unaffected by changes in load. This made it ideal for devices like clocks, power tools, and appliances. Bradley's clever adaptation of synchronous and induction motor principles underpins much of our electrified world today, yet his name remains obscure even among engineering historians.

Printed Circuits

During World War II, radios shrank dramatically in size thanks to a technology called the printed circuit. Pioneered independently by Austrian engineer Paul Eisler and American engineer John Sargrove, printed circuits allowed the wiring of a radio to be condensed onto a single layer.

Previously, radios used bulky and labor-intensive point-to-point wiring - discrete wires individually soldered to terminals. By printing the wiring directly onto boards, radios could be mass produced quickly and cheaply. This miniaturization helped make possible portable radios and radar systems during WWII.

After the war, printed circuits became the standard in the booming consumer electronics industry. Yet few realize that this radical shift in circuit manufacturing originated from wartime research that was kept classified for years.

Selenium Rectifiers

Before the silicon diode's rise to ubiquity, a curios material called selenium enabled early electronics to convert alternating current (AC) into direct current (DC). Discovered accidentally in 1874 by Willoughby Smith, selenium's resistance varied significantly depending on ambient light.

This photoconductive property allowed selenium to act as a primitive solar cell. But in 1933, a Bell Laboratories team led by Cyril Franks found that solid selenium also exhibited asymmetric conductivity, allowing current to pass much more easily in one direction.

The selenium rectifier was born. Unlike fragile glass vacuum tube rectifiers, these crude selenium devices had no filaments to burn out and could handle large currents. Selenium rectifiers powered early TV sets, radios, battery chargers and more. Although extremely inefficient by today's standards, these obscure electronic components paved the way for solid-state electronics.

Magnetic Amplification

In the 1920s, Bell Labs engineer William A. Rheinholdt developed a novel form of amplification called magnetic amplification. This used saturable magnetic cores to amplify signals, performing a function similar to vacuum tube amplifiers. The magnetic amplifier had no moving parts and did not require heated filaments like tubes.

This rugged simplicity made magnetic amplifiers ideal for industrial control systems and heavy military use. Applied widely during WWII, they controlled electromechanical devices like turrets and gun mounts. Magnetic amplifiers persisted into the transistor era thanks to their ability to handle high voltages and currents.

Though eventually phased out by solid-state amplifiers, the magnetic amplifier was a stepping stone that pioneered amplifier principles and applications. Its unique magnetic technology is a largely forgotten part of electrical engineering history.


By shedding light on some of the lesser-known breakthrough innovations in electromagnetism and electronics, we gain a broader understanding of how today's technological world came to be. Often, the famous inventors like Tesla and Edison stand on the shoulders of prior pioneers whose seminal discoveries fade into obscurity.

So the next time we simply plug in our devices without a thought, we should take a moment to appreciate not just the modern conveniences electricity enables, but also the hidden history of experimentation and insight that made it all possible. The obscure inventions profiled here helped electrify the path to our present day.