What is a Transistor: The Switch That Built the Modern World
A tiny switch with no moving parts that powers everything
A tiny switch with no moving parts that powers everything
A transistor has three pins. The base (or gate) is the control. The collector and emitter are where current flows. When you put voltage on the base, current flows from collector to emitter. No base voltage, no flow. Click the BASE switch to try it.
Click the BASE switch to control the transistor.
Wire a transistor in a special way and you get an inverter: input HIGH gives output LOW, input LOW gives output HIGH. This is a NOT gate, the simplest building block in digital logic. Click the input to see how the output flips.
Click the input switch to flip the output.
In 1965, Gordon Moore predicted that the number of transistors on a chip would double every two years. He was right for over 50 years. The y-axis is logarithmic. Each gridline is 10x more transistors. Hover the dots to see specific chips.
Hover a chip to see its transistor count.
A modern transistor gate is about 3 nanometers wide. That is roughly 15 silicon atoms across. For comparison, here's the world at different scales.
About 0.1 millimeters thick. You could stack roughly 33,000 modern transistor gates across the thickness of one sheet of printer paper.
The width of an average human hair. About 25,000 transistor gates would fit side by side across one hair.
One of the smallest things you can see under a basic microscope. Still over 2,000 times wider than a 3nm transistor gate.
You need an electron microscope to see one. A flu virus is about 33 transistor gates wide.
About 15 silicon atoms across. The Apple M3 packs 25,000,000,000 of these onto a chip the size of a fingernail.
The fundamental limit. Engineers are running out of room to shrink. The future is 3D stacking, new materials, and new architectures.
The first transistor, built at Bell Labs in 1947, was big enough to hold in your hand. The inventors won the Nobel Prize. If they'd patented it tightly, the digital revolution might never have happened. Instead, AT&T licensed it cheaply, and the world changed.
You've met the most important invention of the 20th century. A transistor is just a switch controlled by voltage. Stack billions of them on a fingernail-sized chip and you get a CPU. Every phone, game, and rocket ship runs on these tiny switches turning on and off billions of times per second.
Three pins: a control pin (base/gate) and two pins for current to flow between (collector/drain and emitter/source). A small voltage on the control pin lets current flow. No voltage, no flow.
Unlike a light switch, a transistor has zero mechanical parts. It uses semiconductor physics to switch. That means no wear, and they can flip on and off billions of times per second.
Wire a transistor with a resistor and you get a NOT gate (inverter). Combine more and you get AND, OR, and every other gate. From there: math, memory, every program ever written.
In 1965, Gordon Moore predicted transistor count would double every two years. It held for 50+ years. The first chip in 1971 had 2,300 transistors. The Apple M3 has 25 billion.
Put your new knowledge into practice!