Transistors

Electronic (vacuum) valves are wonderful devices. Besides their indispensable use in radio and television sets they do many other jobs. They are used in radar and motion-picture equipment. They control manufacturing processes, and they are basic elements in "electronic brains".

But vacuum valves have a few drawbacks. They waste a good deal of electricity. One of the elements in a vacuum valve must be heated so that it will give off electrons. This heating requires electricity and produces unwanted heat. Imagine how much heat is-produced by the hundreds of valves in the electronic controls of a supersonic jet aeroplane! Such planes have to use special cooling equipment to help get rid of the heat.

Scientists, realizing this and other drawbacks of electronic valves, searched for other ways of doing the jobs that valves do. Then, a few years ago, a new device, the transistor was announced. It did not look very impressive. In fact, it was so small, that you had to look carefully to see it, for many transistors are smaller than the india -rubber on the end of a pencil. Yet some transistors can replace electronic valves hundreds of times their size! Transistors need far less current, and produce far less heat, than comparable electronic valves.

They are.made of small germanium crystals. Germanium is an element crystalline in form. Germanium crystal used in a typical transistor may be less than '/₈, inch square and less than 1/32 inch thick.

There are different types of transistors in use, and still more are being developed. Already you can buy tiny radios and use transistors instead of electron tubes. Television sets and many other types of electronic equipment are using or soon will be using, transistors instead of valves. With transistors all this equipment can be made smaller in size.