Transistors Changed Everything. Here’s How They Work

晶体管改变了一切：它们是如何工作的？

Last week I revealed the sneaky physics behind the “joule thief,” an electrical circuit that lets you squeeze more energy out of seemingly dead batteries. The key, it turned out, was a clever pairing of a transformer and a transistor. But the transistor deserves its own headline, because it’s maybe only the most important invention of the 20th century.

上周，我揭示了“焦耳偷盗者”（joule thief）背后的巧妙物理原理，这是一种能让你从看似没电的电池中榨取更多能量的电路。事实证明，其关键在于变压器和晶体管的巧妙组合。但晶体管值得拥有属于它自己的头条，因为它或许是 20 世纪最重要的发明。

Life would be completely different without transistors. For starters, there would be no personal computers or cell phones, so no Amazon, no video games, no dating apps, no messaging, no streaming, no social media, no Apple Pay or Google Maps, and no AI (hmm). Cars contain billions of transistors. They’re really everywhere. So what is a transistor?

如果没有晶体管，生活将完全不同。首先，将不会有个人电脑或手机，也就没有亚马逊、电子游戏、约会软件、即时通讯、流媒体、社交媒体、Apple Pay 或谷歌地图，更不会有 AI（嗯……）。汽车里包含数十亿个晶体管。它们确实无处不在。那么，什么是晶体管呢？

The best way to understand this pivotal technology is to follow the evolutionary trail, all the way back to the electric relays used in telegraphs in the 1800s.

理解这项关键技术的最好方法是追溯其进化轨迹，一直回到 19 世纪电报中使用的电气继电器。

Electric Relays

电气继电器

Telegraph lines were basically long electrical circuits. And you probably never thought about it before, but they ran on batteries—primitive, low-voltage batteries that filled an entire closet at the telegraph station—because there was no electrical grid back then.

电报线路本质上是长距离的电路。你可能从未想过，它们依靠电池运行——那些原始的、低压的电池甚至填满了电报站的整个壁橱——因为那时还没有电网。

The electric relay, invented in 1835, was a key component in these systems. Basically, it was a switch that turned an electrical current on and off—sort of like the wall switch that you use to turn a light on. But lacking fingers, the relay used a second electric current to flip the switch. Why would you use a current to turn on a current? That’s a good question.

1835 年发明的电气继电器是这些系统中的关键组件。从本质上讲，它是一个开关，用于接通或断开电流——有点像你用来开灯的墙壁开关。但由于没有手指，继电器使用第二股电流来拨动开关。为什么要用电流来控制电流呢？这是一个好问题。

Suppose you wanted to turn on a light in another town 50 miles away. Well, you’d string real long wires on utility poles. Then you could toggle the light on and off, and even use a code with dots and dashes to send text messages. But there was a problem: The longer the wire, the more resistance it had, so not enough current would get through to deliver an intelligible signal.

假设你想点亮 50 英里外另一个城镇的一盏灯。你会沿着电线杆拉起很长的电线。然后你可以开关灯，甚至使用点和划的编码来发送文本信息。但有一个问题：电线越长，电阻就越大，因此没有足够的电流通过来传输清晰的信号。

The solution? Split the circuit into two 25-mile lengths and connect them with a relay. When you closed the switch on the first circuit, it operated the relay, sending the same pattern of current from a second battery through the next circuit and turning on the light.

解决方案是什么？将电路分成两段 25 英里的线路，并用继电器连接它们。当你闭合第一个电路的开关时，它会驱动继电器，从第二个电池发送相同模式的电流通过下一个电路，从而点亮灯泡。

Anyway, relays are still widely used today, and the idea of using a current to turn on another current opened up all kinds of possibilities. In cars, for example, it lets you use low-power dashboard controls to switch on high-power circuits that operate things like starters, headlights, or air conditioners.

总之，继电器在今天仍被广泛使用，而利用一股电流来控制另一股电流的想法开启了各种可能性。例如在汽车中，它让你能够使用低功率的仪表盘控制装置来开启高功率电路，从而操作启动器、前灯或空调等设备。

Vacuum Tube

真空管

You can think of a vacuum tube as a modified light bulb. An incandescent light is just a thin wire that gets super hot when current runs through it, so that it glows. That filament is put inside a glass container, and the air is pumped out so the filament doesn’t burn. (That’s the whole purpose of the bulb—to keep out oxygen.)

你可以把真空管看作是改良版的灯泡。白炽灯只是一根细导线，当电流通过时会变得极热，从而发光。灯丝被放置在玻璃容器内，空气被抽走，这样灯丝就不会烧毁。（这就是灯泡的全部目的——隔绝氧气。）

But there’s something else that happens, which you can’t see: When the filament gets super hot, electrons are ejected from it. Since a flow of electrons is an electric current, you can use these thermal electrons in a way that’s similar to a relay.

但还有一件你看不见的事情在发生：当灯丝变得极热时，电子会从中发射出来。由于电子流就是电流，你可以以类似于继电器的方式利用这些热电子。

So this is again a current switch, and just like the relay, it’s controlled by a different wire. But there are two big differences: First, there’s no mechanical contact, which means the output current can change much faster. Second, the output current is not just on or off; it can vary with the strength of the control voltage.

所以这又是一个电流开关，就像继电器一样，它由另一根导线控制。但有两个巨大的区别：第一，没有机械接触，这意味着输出电流的变化速度快得多。第二，输出电流不仅仅是开或关；它可以随着控制电压的强度而变化。

This is what made the first audio amplifiers possible. If you had a weak signal from a distant radio station, it would not produce enough current to drive a speaker so that you could hear anything. But if you fed that signal into the control voltage in a vacuum tube, you could get an output that’s much stronger yet maintains the same pattern (like music) as the original signal.

这使得第一批音频放大器成为可能。如果你从遥远的广播电台接收到一个微弱的信号，它产生的电流不足以驱动扬声器让你听到声音。但如果你将该信号输入到真空管的控制电压中，你就能获得一个更强、但保持与原始信号相同模式（如音乐）的输出。

But wait! There’s something else you could do with vacuum tubes—you could build a computer. Yes, early computers were just a bunch of vacuum tubes controlled by other vacuum tubes, creating logic gates.

等等！你还可以用真空管做另一件事——制造计算机。是的，早期的计算机只是一堆由其他真空管控制的真空管，从而构成了逻辑门。

Actually, you could have built a computer with electric relays. But relays are much slower than vacuum tubes, and all that clicking and clacking would have been maddening. Vacuum tubes were silent, purely electronic components, with no moving parts, and that was a game changer.

事实上，你本可以用电气继电器制造计算机。但继电器的速度比真空管慢得多，而且那所有的咔哒声会让人抓狂。真空管是无声的、纯电子的组件，没有移动部件，这彻底改变了游戏规则。

Transistor

晶体管

Still, there were three problems with vacuum tubes. They used a lot of power, so early computers ran hot, required massive cooling systems, and were prone to burning out.

尽管如此，真空管仍存在三个问题。它们消耗大量电力，因此早期计算机运行温度很高，需要庞大的冷却系统，并且容易烧毁。