Are vacuum tubes the same as light bulbs? What purpose do they serve?
In: Technology
Not the same.
They work like a transistor, but with considerable losses from heat, which is necessary for their operation.
They are wonderous things of voodoo and black magic.
Vacuum tubes are a broad category of electrical device. They’re tubes with their air evacuated, and their purposes/designs vary widely.
These days, they’ve been almost completely replaced with semiconductors like transistors, but they used to be fairly common.
Old CRT monitors and TVs were just huge vacuum tubes which contained an electron beam that drew the picture onto the inside of the glass where the screen is.
One important use of vacuum tubes was as an amplifier. Similar in purpose to the transistor, these things could produce or amplify radio signals. This made them important in early signaling and radar systems.
Not exactly. Light bulbs do have a near vacuum in them, or some times a low pressure of another gas.
But “vacuum tubes” refers to electronic components that did the job of our current day transistors. Basically fast acting electronic switches.
They allow dust to travel from the surface attachment to the collection device, usually a bag or cannister on the cleaner.
A vacuum tube (or thermionic valve to give it it’s alternative title) is a completely different thing from a lightbulb.
The only similarity is the glass housing, and the fact that there is a heating element inside the valve that glows – this is glowing the same as the heating elements in a toaster (which is basically a very inefficient lightbulb) however this is only a side effect of one component inside the valve and not the main function of the circuitry.
The modern replacement for the valve is the transistor – this is a small electrical component that functions as a variable switch, so can be used within a circuit as a form of amplifier or switch.
The main use of valves nowadays is in audio amplifiers – the way valves work is slightly different than transistors, which in the audio world means a slightly different sound reproduction. In particular they are known for the way they start to break up and fail when you push them really hard – which is the original cause of the distortion you hear in a lot of guitar music, and also the audio quality and response in high end equipment.
For most normal people they are finicky, outdated and inefficient technology, completely replaced by the much more efficient transistors – allowing us to replace things like mains powered amplifier the size of an Xbox with the tiny amplifier on a chip that lives inside your phone.
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