Vacuum tube

In electronics, a vacuum tube, an electron tube, or just a tube (North America), or valve (Britain and some other regions) is a device that controls electric current between electrodes in an evacuated container. Vacuum tubes mostly rely on thermionic emission of electrons from a hot filament or a cathode heated by the filament. This type is called a thermionic tube or thermionic valve. A phototube, however, achieves electron emission through the photoelectric effect. Not all electronic circuit valves/electron tubes are vacuum tubes (evacuated); gas-filled tubes are similar devices containing a gas, typically at low pressure, which exploit phenomena related to electric discharge in gases, usually without a heater.

The simplest vacuum tube, the diode, contains only a heater, a heated electron-emitting cathode (the filament itself acts as the cathode in some diodes), and a plate (anode). Current can only flow in one direction through the device between the two electrodes, as electrons emitted by the cathode travel through the tube and are collected by the anode. Adding one or more control grids within the tube allows the current between the cathode and anode to be controlled by the voltage on the grid or grids. Tubes with grids can be used for many purposes, including amplification, rectification, switching, oscillation, and display.

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Latest News for: vacuum-tube

Il Sereno, Lake Como reopens for 2025, introducing the exclusive Listening Suite

TravelDailyNews 24 Mar 2025
At its heart lies a state-of-the-art sound system featuring audio equipment including vacuum tube amplifiers, a refurbished reel-to-reel players and speakers made from the same wood as the rest of the ...

For decades I was brushed off by doctors over my chunky painful legs - then ...

The Daily Mail 21 Mar 2025
They also constantly ached and were prone to bruising, and no amount of dieting or exercise seemed to help ... Liposuction, where a tube is inserted through incisions in the skin, and a vacuum is used to suck out the fat cells is another option ... NHS. .

China’s Maglev rescues Elon Musk’s dream from oblivion, slashing build costs by 60%

Interesting Engineering 20 Mar 2025
A futuristic transport system built around near-vacuum tubes designed to whisk passengers between cities at speeds of up to 1,000 km/h (621 mph).  ... complexity and cost of vacuum tube travel.

How China is solving the nightmare that killed Elon Musk’s Hyperloop

South China Morning Post 20 Mar 2025
Chinese engineers have overcome the hurdles that stopped the US billionaire’s idea for a vacuum tube transport system in its tracks ... .

Maple Weekend: Savor a sweet treat at local sugar shacks this March

Democrat & Chronicle 20 Mar 2025
Maple syrup makers near Erie PA boil sap for NWPA Maple Taste & Tour ... Maple Weekend is 10 a.m. to 4 p.m ... The operation has evolved technologically, using tubing, vacuum pumps and reverse osmosis now, from early days of sap bucket collection ... to 4 p.m.

How does human body change in deep space?

The News International 18 Mar 2025
— Reuters ... To counteract this, astronauts use three exercise machines on the ISS, including a 2009-installed resistance device that simulates free weights using vacuum tubes and flywheel cables. A two-hour daily workout keeps them in shape ... .

Railways minister Ashwini Vaishnaw visits IIT Madras, pledges support for Hyperloop, ePlane, and SHAKTI projects

The Times of India 18 Mar 2025
MUMBAI ... V. Kamakoti, Prof ... I'm so happy to see young, energetic engineers working on this new technology and doing new experiments ... V ... Hyperloop technology enables high-speed travel in near-vacuum tubes, allowing speeds exceeding 1000 km/h ... V ... .

Vision impairment, balance disruption: What happens to human body in deep space?

Hindustan Times 18 Mar 2025
9, 2024.(AP File) ... Also read ... Also read ... To counteract physical degradation, astronauts use three exercise machines on the ISS, including a 2009-installed resistance device that simulates free weights using vacuum tubes and flywheel cables ... Also see .

What happens to the human body in deep space?

Hong Kong Standard 18 Mar 2025
- Exercise key -. The Standard Channel. IOS Android. IOS Android ... To counteract this, astronauts use three exercise machines on the ISS, including a 2009-installed resistance device that simulates free weights using vacuum tubes and flywheel cables ... AFP. .

India to have ‘world’s longest hyperloop tube soon’: Vaishnaw shares video

The Times of India 17 Mar 2025
soon to be the world's longest @iitmadras.”— AshwiniVaishnaw (@AshwiniVaishnaw) Hyperloop technology is considered the fifth mode of transportation, involving high-speed pods travelling in a near-vacuum tube.

India's Hyperloop tube to soon become world's longest at 410 metres

Khaleejtimes 17 Mar 2025
The Hyperloop tube, being developed with the help of the Indian Institute of Technology Madras, is soon set to be the world's longest tube, measuring 410 metres in length ... Hyperloop is a high-speed train that runs in a vacuum in a tube.

‘World’s longest’ 1,345-foot hyperloop track could trial run at 621 mph speed

Interesting Engineering 17 Mar 2025
The facility is a critical step in advancing Hyperloop technology, a revolutionary mode of transportation that propels pods through near-vacuum tubes at speeds exceeding 621 mph (1,000 km/h).

World's longest Hyperloop tube being developed at IIT Madras: Ashwini Vaishnaw

Hindustan Times 16 Mar 2025
Union minister Ashwini Vaishnaw visited Hyperloop testing facility at IIT Madras on Saturday and said that the 410-meter Hyperloop tube would soon become the world's longest high-speed tube, reported news agency ANI ... Vacuum, magnetic fields.

Hyperloop tube in India to soon become world's longest at 410 meters: Ashwini Vaishnaw

Business Line 16 Mar 2025
The 410-meter-long Hyperloop test tube located at IIT Madras is already the longest Hyperloop test facility in Asia. Hyperloop is a high-speed train that runs in a vacuum in a tube.
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