Ten real vacuum tubes and valve-era devices: Fleming valves, radio valves, triodes, a Nuvistor, a Nixie tube, a magnetron, and a photomultiplier. Photograph credits: 1. File:Fleming valves.jpg; John Ambrose Fleming; Public domain; ; https://commons.wikimedia.org/wiki/File:Fleming_valves.jpg; 2. File:12C3C.jpg; Mister rf; CC BY-SA 4.0; https://creativecommons.org/licenses/by-sa/4.0; https://commons.wikimedia.org/wiki/File:12C3C.jpg; 3. File:RCA ’808’ Power Vacuum Tube.jpg; 池田正樹 ( talk )masaki ikeda; Public domain; ; https://commons.wikimedia.org/wiki/File:RCA_%E2%80%99808%E2%80%99_Power_Vacuum_Tube.jpg; 4. File:Vacuum tube Cymotron UX171-A triode IMG 7855.jpg; Alex P. Kok; CC BY-SA 4.0; https://creativecommons.org/licenses/by-sa/4.0; https://commons.wikimedia.org/wiki/File:Vacuum_tube_Cymotron_UX171-A_triode_IMG_7855.jpg; 5. File:Vacuum tube Telefunken REN2204 triode IMG 7979.jpg; Alex P. Kok; CC BY-SA 4.0; https://creativecommons.org/licenses/by-sa/4.0; https://commons.wikimedia.org/wiki/File:Vacuum_tube_Telefunken_REN2204_triode_IMG_7979.jpg; 6. File:Vacuum tube Philips ECH3 triode hexode IMG 7888.jpg; Alex P. Kok; CC BY-SA 4.0; https://creativecommons.org/licenses/by-sa/4.0; https://commons.wikimedia.org/wiki/File:Vacuum_tube_Philips_ECH3_triode_hexode_IMG_7888.jpg; 7. File:Hitachi 7586 Nuvistor triode tube.jpg; Mister rf; CC BY-SA 4.0; https://creativecommons.org/licenses/by-sa/4.0; https://commons.wikimedia.org/wiki/File:Hitachi_7586_Nuvistor_triode_tube.jpg; 8. File:ZM1210-operating edit2.jpg; Georg-Johann Lay with a slight edit by Richard Bartz; CC BY-SA 3.0; http://creativecommons.org/licenses/by-sa/3.0/; https://commons.wikimedia.org/wiki/File:ZM1210-operating_edit2.jpg; 9. File:725A Magnetron Tube, Raytheon, World War II - National Electronics Museum - DSC00140.JPG; Daderot; CC0; http://creativecommons.org/publicdomain/zero/1.0/deed.en; https://commons.wikimedia.org/wiki/File:725A_Magnetron_Tube,_Raytheon,_World_War_II_-_National_Electronics_Museum_-_DSC00140.JPG; 10. File:RMA 1P21 photomultiplier tube.jpg; Ladd Observatory; CC BY-SA 4.0; https://creativecommons.org/licenses/by-sa/4.0; https://commons.wikimedia.org/wiki/File:RMA_1P21_photomultiplier_tube.jpg;