Diagram of Vacuum-Tube DiodeDiagram of Vacuum-Tube TriodeInside of a vacuum tube with plate cut open.A two-tube homemade radio from 1958. The tubes are the two glass columns with the dark tops. The leads at the bottom connect to the low-voltage filament supply and to the high-voltage anode supplyAn RCA 12AX7 dual-triode tube (1947)

Discover great deals on the many top brand items available only on eBay!


This site contains sponsored affiliate links.

Vacuum Tubes

In electronics, a vacuum tube (U.S. and Canadian English) or (thermionic) valve (outside North America) is a device generally used to amplify, or otherwise modify, a signal by controlling the movement of electrons in an evacuated space. more...

HomeHome
Accessories & CablesAccessories & Cables
AmplifiersAmplifiers
CD Players & RecordersCD Players & Recorders
Cassette DecksCassette Decks
CrossoversCrossovers
DVD Players & Recorders DVD Players & Recorders
Digital Music...Digital Music...
Digital Video Recorders, PVRDigital Video Recorders, PVR
EqualizersEqualizers
Headphones, HeadsetsHeadphones, Headsets
Home Audio MiscHome Audio Misc
Home Theater ProjectorsHome Theater Projectors
Home Theater in a Box Home Theater in a Box
KaraokeKaraoke
MiniDisc PlayersMiniDisc Players
OtherOther
PreamplifiersPreamplifiers
ProcessorsProcessors
RadiosRadios
ReceiversReceivers
Remote ControlsRemote Controls
Satellite Radio Satellite Radio
Satellite, Cable TVSatellite, Cable TV
Shelf, Compact SystemsShelf, Compact Systems
Speakers & SubwoofersSpeakers & Subwoofers
Televisions TVTelevisions TV
Tuners, AM/FMTuners, AM/FM
TurntablesTurntables
VCRsVCRs
Vintage ElectronicsVintage Electronics
8-Track Players8-Track Players
Amplifiers, Tube AmpsAmplifiers, Tube Amps
Books, Manuals, MagazinesBooks, Manuals, Magazines
CapacitorsCapacitors
Cassette DecksCassette Decks
Drivers & HornsDrivers & Horns
Other VintageOther Vintage
Preamplifiers, Tube PreampsPreamplifiers, Tube Preamps
RadiosRadios
ReceiversReceivers
Reel-to-Reel Tape RecordersReel-to-Reel Tape Recorders
SpeakersSpeakers
TelephonesTelephones
TelevisionsTelevisions
TransformersTransformers
TubesTubes
NOS TubesNOS Tubes
Other TubesOther Tubes
Tube SocketsTube Sockets
Vacuum TubesVacuum Tubes
General ElectricGeneral Electric
MullardMullard
Other BrandsOther Brands
RCARCA
SylvaniaSylvania
Western ElectricWestern Electric
Tuners, Tube TunersTuners, Tube Tuners
TurntablesTurntables
Wholesale LotsWholesale Lots

Once used in most electronic devices, vacuum tubes are now used only in specialized applications. For most purposes, the vacuum tube has been replaced by the much smaller and less expensive transistor, either as a discrete device or in an integrated circuit. At the start of the 21st century there has been renewed interest in the vacuum tube, this time in the form of the Field-emitter microtube.

Operation

Vacuum tubes, or thermionic valves, are arrangements of electrodes in a vacuum within an insulating, temperature-resistant envelope. Although the envelope was classically glass, power tubes often use ceramic and metal. The electrodes were attached to leads which passed through the envelope in a way that was sealed air tight. On most tubes, the leads were designed to plug into tube sockets for easy replacement.

The simplest vacuum tubes resemble incandescent light bulbs in that they have a filament sealed in a glass envelope which has been evacuated of all air. When hot, the filament releases electrons into the vacuum: a process called thermionic emission. The resulting negatively-charged cloud of electrons is called a space charge. These electrons will be drawn to a metal plate inside the envelope if the plate (also called the anode) is positively charged relative to the filament (or cathode). This results in a current of electrons flowing from filament to plate. This cannot work in the reverse direction because the plate is not heated and cannot emit electrons. This very simple example described can thus be seen to operate as a diode: a device that conducts current only in one direction.

Development

John Ambrose Fleming, scientific adviser to the Marconi company invented the diode in 1904 based on an observation by Thomas Edison (Edison received U.S. Patent 307031 from this observation). The unidirectional current and construction of the original diode led to Lee DeForest placing another electrode, a bent wire or screen, between the filament and plate electrode in 1906. DeForest discovered that the current flow from filament to plate depended on the voltage applied to the grid, and that the current drawn by the grid was very low, being composed of the electrons which are intercepted by the grid. As the applied voltage of the grid varied from negative to positive, the current of electrons flowing from the filament to the plate would vary accordingly. Thus the grid was said to electrostatically "control" the plate current. The resulting three-electrode device was therefore an excellent and very sensitive amplifier of voltages. DeForest called his invention the audion, but it is better known as a triode. The tube equivalent of a transistor, triodes were used in early tube amplifiers.

Read more at Wikipedia.org


[List your site here Free!]

(qty 1) Antique Globe Style Vacuum Tubes - Duds - 01 12 26 27 30 71 47 80 etc(qty 1) Antique Globe Style Vacuum Tubes - Duds - 01 12 26 27 30 71 47 80 etc $2.80 12Ba6 2 Tubes New (New Old Stock) Test New 1 Year Warranty12Ba6 2 Tubes New (New Old Stock) Test New 1 Year Warranty $8.45
Lot of 110+ Nos Boxed Vintage Sylvania Radio/Tv Vacuum TubesLot of 110+ Nos Boxed Vintage Sylvania Radio/Tv Vacuum Tubes $200.00 Matched Pair Nos Jan • 12Sl7Gt Cv 924 Vacuum TubesMatched Pair Nos Jan • 12Sl7Gt Cv 924 Vacuum Tubes $150.00
New ListingPair Sylvania 6Sn7Gt Vt-231 Tubes 2 Hole Bad Boys Closely MatchedNew ListingPair Sylvania 6Sn7Gt Vt-231 Tubes 2 Hole Bad Boys Closely Matched $99.99 Rca 2050 Electron Vacuum Tube’s Untested New Old Stock VintageRca 2050 Electron Vacuum Tube’s Untested New Old Stock Vintage $13.41
Sleeve of 5 ea Jan 6189W Vacuum Tubes Sylvania Tested Nos Military Spec 12Au7Sleeve of 5 ea Jan 6189W Vacuum Tubes Sylvania Tested Nos Military Spec 12Au7 $80.00 Vacuum Tube, 12Ax7 / Ecc83, Jj Electronics, Standard Pins, PreampVacuum Tube, 12Ax7 / Ecc83, Jj Electronics, Standard Pins, Preamp $18.95
New Listing2 Excellent Nos Nib Graphite Ge 6336A Pair Vacuum Tubes MatchingNew Listing2 Excellent Nos Nib Graphite Ge 6336A Pair Vacuum Tubes Matching $45.00 Matched Lot of (3) Jan-Cz-C1K National Electronics Untested Vacuum TubesMatched Lot of (3) Jan-Cz-C1K National Electronics Untested Vacuum Tubes $49.95
Pair of Kt88 Power Vacuum TubePair of Kt88 Power Vacuum Tube $99.00 6Sj7 Vacuum Tubes Various Brands All Tested as Nos Good ( Qty 1 )6Sj7 Vacuum Tubes Various Brands All Tested as Nos Good ( Qty 1 ) $2.95
2 Amperex 6Ca7 El84 Electron Amplifier Radio Vacuum Tubes Tv-7 Tested T3102 Amperex 6Ca7 El84 Electron Amplifier Radio Vacuum Tubes Tv-7 Tested T310 $299.00 New Gain Matched Quintet (5) Jj Electronics Tesla 12Ax7 Ecc83-S Vacuum TubesNew Gain Matched Quintet (5) Jj Electronics Tesla 12Ax7 Ecc83-S Vacuum Tubes $98.12
One Pair (2) Nos 1950's Rca 12Au7 Vacuum Tube Gray Plate Angled Slant GetterOne Pair (2) Nos 1950's Rca 12Au7 Vacuum Tube Gray Plate Angled Slant Getter $39.99 Nos/Nib Pair Rca 6Sj7 Vacuum Tube - Matched Code. / 1954Nos/Nib Pair Rca 6Sj7 Vacuum Tube - Matched Code. / 1954 $29.44
1x 5U4Gb Vintage Usa Rectifier Vacuum Tube One Year Warranty1x 5U4Gb Vintage Usa Rectifier Vacuum Tube One Year Warranty $6.00 New ListingWestern Electric 247A Vacuum Tube Tv7 Tested StrongNew ListingWestern Electric 247A Vacuum Tube Tv7 Tested Strong $95.00
Type 75 vacuum tubes radio, Tv, Ham, tested and repackaged, usedType 75 vacuum tubes radio, Tv, Ham, tested and repackaged, used $15.00 Matched Quad Ge Jg-6829 Mil-spec (12Av7) Vacuum Tubes / Triple Mica-Grey PlateMatched Quad Ge Jg-6829 Mil-spec (12Av7) Vacuum Tubes / Triple Mica-Grey Plate $84.00
Rca 12Bz6 Vacuum Tube Nos /Nib Sq Getter Tested ( Qty One Tube ) 1969Rca 12Bz6 Vacuum Tube Nos /Nib Sq Getter Tested ( Qty One Tube ) 1969 $12.95 Type 75 ~ National Brand Vacuum Tube(s) ▪︎ Fast Shipping & Just Tested Good!Type 75 ~ National Brand Vacuum Tube(s) ▪︎ Fast Shipping & Just Tested Good! $13.95
Raytheon Jan 5678 Vacuum Tube Nos/Nib ( Qty 5 )Raytheon Jan 5678 Vacuum Tube Nos/Nib ( Qty 5 ) $8.95 3 Tung-Sol Vacuum Tubes - Tested, Vintage Audio Amplifier Tubes3 Tung-Sol Vacuum Tubes - Tested, Vintage Audio Amplifier Tubes $75.00
Matched Pair Tung Sol 12Ax7 / Ecc83 pre-amp tubes, Brand New in Box !Matched Pair Tung Sol 12Ax7 / Ecc83 pre-amp tubes, Brand New in Box ! $49.95 Vintage Rca 12Au7A Platinum Grade Clear Top Preamp Tubes Matched Pair 90%+ NosVintage Rca 12Au7A Platinum Grade Clear Top Preamp Tubes Matched Pair 90%+ Nos $34.95
General Electric Ge 12Au7A 12Au7 Vacuum Tubes Usa Lot Of 5 Gray Box PlatesGeneral Electric Ge 12Au7A 12Au7 Vacuum Tubes Usa Lot Of 5 Gray Box Plates $17.55 New In Box Gain Matched Trio (3) Jj Electronics Tesla 12Ax7 Ecc83-S Vacuum TubesNew In Box Gain Matched Trio (3) Jj Electronics Tesla 12Ax7 Ecc83-S Vacuum Tubes $62.42
Pair Western Electric Vt1 Metal Base Vacuum TubePair Western Electric Vt1 Metal Base Vacuum Tube $100.00 Nos/Nib Marconi Jan 12Sc7 Vacuum TubesNos/Nib Marconi Jan 12Sc7 Vacuum Tubes $2.25
12Ax7 Style Vacuum Tube Amber Led Night Light made w/ Valve from Peavey Mesa Amp12Ax7 Style Vacuum Tube Amber Led Night Light made w/ Valve from Peavey Mesa Amp $29.95 12av7 Nos Vacuum Tube12av7 Nos Vacuum Tube $4.99
Ge Vintage Vacuum Tubes - 12Bh7 (747 Tested) (2 pack)Ge Vintage Vacuum Tubes - 12Bh7 (747 Tested) (2 pack) $16.99 New ListingPair of Sylvania 12Au7 Vintage Usa Vacuum Tubes, Nos, Tested & StrongNew ListingPair of Sylvania 12Au7 Vintage Usa Vacuum Tubes, Nos, Tested & Strong $27.00
New Listing7208 Lot Of 15 12At7 Vacuum TubesNew Listing7208 Lot Of 15 12At7 Vacuum Tubes $15.99 2x Vintage El32 Mullard vacuum tubes2x Vintage El32 Mullard vacuum tubes $59.59
Vacuum Tube, 12Dw7 / Ecc832, Jj Electronics, Dual Triode, Standard Pins, PreampVacuum Tube, 12Dw7 / Ecc832, Jj Electronics, Dual Triode, Standard Pins, Preamp $20.59 New Listingunited Vt-166 Vacuum TubeNew Listingunited Vt-166 Vacuum Tube $25.00
New ListingPair Nib Ge 12Ax7 Ecc83 vacuum tube - D getter-Black Plate -1950's premiun MatchNew ListingPair Nib Ge 12Ax7 Ecc83 vacuum tube - D getter-Black Plate -1950's premiun Match $137.19 (3) Sylvania 6L6Gc Str-387/Str387 Vacuum Tubes Matched Pair Tested(3) Sylvania 6L6Gc Str-387/Str387 Vacuum Tubes Matched Pair Tested $36.00
New ListingLot Of (20) 12By7A - Radio Vacuum Valve Tubes - Mixed BrandsNew ListingLot Of (20) 12By7A - Radio Vacuum Valve Tubes - Mixed Brands $9.99 Rca Oc3 Radio Vacuum Tubes In Original Box ~ T60Rca Oc3 Radio Vacuum Tubes In Original Box ~ T60 $19.95
New Listing6 Ge 6Sn7 Vacuum Tubes Tv-7 TestedNew Listing6 Ge 6Sn7 Vacuum Tubes Tv-7 Tested $49.99 12ax7 tubes pair Channel Master Audiophile Nos12ax7 tubes pair Channel Master Audiophile Nos $109.69
New ListingType 17Jb6 vacuum tubes radio, Tv, Ham, tested and repackaged, usedNew ListingType 17Jb6 vacuum tubes radio, Tv, Ham, tested and repackaged, used $12.50 12Ax7A Baldwin Vintage Vacuum Tubes (2)12Ax7A Baldwin Vintage Vacuum Tubes (2) $46.00
New ListingBox Lot - 160+ Vintage Tubes, 6bz6, 12au6, 6ak5, 6be6, 6bq7, etc.New ListingBox Lot - 160+ Vintage Tubes, 6bz6, 12au6, 6ak5, 6be6, 6bq7, etc. $25.00 12Sj7 Vacuum Tube (1), Us Manufacturers, Nos Testing Strong12Sj7 Vacuum Tube (1), Us Manufacturers, Nos Testing Strong $2.95
One Tested 12At7 Vacuum Tube One Tube OnlyOne Tested 12At7 Vacuum Tube One Tube Only $6.99 New ListingType 6Ge5 vacuum tubes radio, Tv, HaM, tested and repackaged, usedNew ListingType 6Ge5 vacuum tubes radio, Tv, HaM, tested and repackaged, used $10.00
Ecc83 Halltron vacuum tubesEcc83 Halltron vacuum tubes $30.00 Vintage Tested Strong Ge 12Sg7 Amplifier Radio Metal Vacuum TubeVintage Tested Strong Ge 12Sg7 Amplifier Radio Metal Vacuum Tube $4.00
4 Nos Raytheon Jan 6418 Sub-Miniature Vacuum Tubes - Pentodes for Radio & Audio4 Nos Raytheon Jan 6418 Sub-Miniature Vacuum Tubes - Pentodes for Radio & Audio $24.00 Nos Ge Type 42 Vacuum TubeNos Ge Type 42 Vacuum Tube $14.95
New ListingLot Of 11 Ge,Sylvania,Rca,6Sn7Gta/G tb Vacuum Tubes Tv-7 Tested.New ListingLot Of 11 Ge,Sylvania,Rca,6Sn7Gta/G tb Vacuum Tubes Tv-7 Tested. $87.00 2 Nos Nib Rca 12At7Wa / 12At7 Audio Vacuum Tubes Usa Made (Many Available)2 Nos Nib Rca 12At7Wa / 12At7 Audio Vacuum Tubes Usa Made (Many Available) $45.00
5x Nos Ge Jan 5654W / 6Ak5 - Audio Radio Preamp Tubes 5 Pack Sleeve Free Ship5x Nos Ge Jan 5654W / 6Ak5 - Audio Radio Preamp Tubes 5 Pack Sleeve Free Ship $26.99 Lot of 32 Tung-Sol Electron Tubes - Assorted Models, Vintage Vacuum TubesLot of 32 Tung-Sol Electron Tubes - Assorted Models, Vintage Vacuum Tubes $125.00
Nos Nib Tung Sol 24A (24-A , 224) Vintage Radio Vacuum Tubes *Price Per Tube*Nos Nib Tung Sol 24A (24-A , 224) Vintage Radio Vacuum Tubes *Price Per Tube* $13.95 6A8/G/Gt- 100% Tested Good Vacuum Tube- Tests Strong6A8/G/Gt- 100% Tested Good Vacuum Tube- Tests Strong $15.75
Takatsuki Ta−300B Vacuum Tubes (matched pair)Takatsuki Ta−300B Vacuum Tubes (matched pair) $1,599.00 Vintage Vacuum Tube #224Vintage Vacuum Tube #224 $10.75
Pair of Nos Groove Tube Gt-12Au7A / 12Au7 Audio Vacuum Tubes (Many Available)Pair of Nos Groove Tube Gt-12Au7A / 12Au7 Audio Vacuum Tubes (Many Available) $29.98 New ListingLot Of 3 813 Vacuum Tubes UntestedNew ListingLot Of 3 813 Vacuum Tubes Untested $75.00
Jj Electronics Vacuum Tube - Kt88Jj Electronics Vacuum Tube - Kt88 $55.00 (1) Electron Tube Ge Jan 5670w Twin Triode Vacuum tubes. Nos(1) Electron Tube Ge Jan 5670w Twin Triode Vacuum tubes. Nos $12.00
Click to see more Vacuum Tubes items at www.ebay.com
Prices current as of last update, 03/24/25 4:50pm.

See also...
General Electric, Vacuum Tubes, Tubes, Vintage Electronics
Mullard, Vacuum Tubes, Tubes, Vintage Electronics
Other Brands, Vacuum Tubes, Tubes, Vintage Electronics
RCA, Vacuum Tubes, Tubes, Vintage Electronics
Sylvania, Vacuum Tubes, Tubes, Vintage Electronics
Western Electric, Vacuum Tubes, Tubes, Vintage Electronics

Home Contact Resources Exchange Links ebay