because if it was heated in open air it would burn up
Thermionic Emission
Tube Choke Condensor Vibrator (used in HV battery supplies) Valve is another term for vacuum tube, used in old radios.
BIPOLAR A2 It does not stand for anything. It is a maker's designation mark, a throwback from the thermionic tube (valve) days. The letters in front of the number used to indicate the heater voltage and the type of internals (triode, pentode etc) B used to indicate that it was a semiconductor, not a tube. There are different designations around the world, for the same equivalent device, American, European and Japanese.
2 states
It means that the glass envelope has leaked and is no longer a vacuum. Air inside has oxidized the getter. They generally no longer work in this condition.
the earliest synthesizers used a variety of thermionic-valve (vacuum tube) and electro-mechanical technologies.
Emrys Williams has written: 'Thermionic valve circuits' -- subject(s): Vacuum-tube circuits
Yes; solid state rectifiers were made using values (also called vacuum tubes). ************************************************************* A solid state device is a semiconductor device. A valve (vacuum tube) is a thermionic device, so yes, rectification can be achieved with a thermionic rectifier.
Both time and temperature can decrease the vacuum draw of an evacuated tube. Hence the provided expiration dates and storage temperature of tubes. The vacuum of a tube will decrease if it is too old or if stored at a colder temperature than recommended.
The EL34 is a type of vacuum tube, otherwise known as a thermionic valve. It is typically used in audio amplification circuits as a series regulator. They are found in some high-powered audio amplifiers.
Vacuum tubes are typically evacuated of gases to create a vacuum inside. However, some specialized vacuum tubes may use inert gases like argon or neon to improve performance or provide specific characteristics.
Thermionic emission occurs at the cathode in a cathode ray tube, which is a vacuum tube that generates electron beams. When the cathode is heated, electrons are emitted and accelerated towards the anode, leading to the generation of cathode rays within the tube.
Valve is another term for vacuum tube, used in old radios.
In Great Britain its also called "Valve"
ENIAC,EDSAC,EDVAC,UNIVAC(I &II) and MARKS1
It's a thermionic valve/electron tube with *two* triodes in the one envelope. Examples: 3A5, 6J6, 6SN7/6SL7, 12AU7/12AX7, ECC32, ECC82.
They were called thermionic valves. there was also the cathode ray tube (CRT)