Week 21: Tube amplifier

What is this contraption?

How old is it?

Are these still used today?

Tube amplifier

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Answers:

What is this contraption?

It looks kind of like a complicated light bulb, doesn't it? That's because it puts some of the same ideas to a different use. But unlike a light bulb, which is filled with inert gas, the inside of this tube is a vacuum. The vacuum makes it possible for the electrons to flow in such a way as to convert the current from alternating (AC) to direct current (DC). We won't go deeply into how it works, because it gets pretty technical, but what it does is it uses electricity to amplify a radio frequency (RF) signal. So we would call this contraption a "vacuum tube RF amplifier."

How old is it?

This tube amplifier was donated to the Karshner Museum in 1958. When it was new it cost over $200, which in today's dollars is estimated at over $1500.

Are these still used today?

The triode was a milestone invention, because in the first half of the 20th century it helped to greatly extend the range of both radio and the telephone network. But for the most part they have been replaced by transistors, which are much smaller and cheaper.