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时光倒退几十年,人们使用的大都还是电子管收音机:打开电源开关,要等1分多钟,收音机才会慢慢地响起来。这种收音机普遍使用五六个电子管,输出功率只有1瓦左右。但是,就是这种简陋的、功能有限的收音机,给当时的人们带来了无穷的欢乐。 说起电子管,我们首先得从“爱迪生效应”谈起。爱迪生这位举世闻名的大发明家,在研究白炽灯的寿命时,在灯泡的碳丝附近焊上一小块金属片。结果,他发现了一个奇怪的现象:金属片虽然没有与灯丝接触,但如果在它们之间加上电压,灯
Time back decades, most people use the tube radio: turn on the power switch, wait a minute or more, the radio will slowly ring it. This radio commonly used five or six tubes, the output power of only about 1 watt. However, this simple, limited-function radio has brought immense joy to the people of that time. Speaking of tubes, we first have to talk about the “Edison effect.” Edison, the world-famous inventor, studied the life of an incandescent lamp by welding a small piece of metal near the filament of a light bulb. As a result, he found a strange phenomenon: although the metal sheet is not in contact with the filament, but if the voltage is applied between them, the lamp