What Is This Thing? The Mysterious Wooden Ford Box Found in an Old Building

At first glance, this old wooden box looks like some kind of antique electrical device or mechanical component. The Ford name stamped into the top is the biggest clue—but what exactly was it used for?

The answer takes us back more than a century, to the early days of automobile engineering.

This is an ignition coil from a Ford Model T, commonly known as a Model T trembler coil or “buzz coil.” These small wooden-cased devices were an essential part of the Model T’s ignition system. (Science Museum Group Collection)

🚗 A Small Box With a Very Important Job

The Ford Model T was produced from 1908 to 1927, and its ignition system was quite different from the systems found in modern cars.

Instead of using a modern distributor and individual electronic ignition coils, the Model T used four separate ignition coils—one for each cylinder.

Each coil was housed in a small wooden box like the one shown in the photograph. (Science Museum Group Collection)

That means this seemingly ordinary wooden box was actually responsible for helping produce the electrical spark needed to ignite the fuel inside one cylinder of the engine.

⚡ How Did a Model T Ignition Coil Work?

The device used what is known as a trembler coil.

When electrical current from the car’s battery passed through the coil, it created a magnetic field. That magnetic field pulled a small armature, which opened the electrical contacts.

When the contacts opened, the magnetic field collapsed and produced a much higher voltage in the secondary winding.

The process happened repeatedly, creating the characteristic rapid buzzing sound that gave these devices their nickname: “buzz coils.” (World Radio History)