Special Indicators (Vintage)
The basic types of vintage indicators are (1) Neon (or Argon), (2)Triode like miniature Cathode Ray Tube ( (3) Vacuum Fluorescent Display (VFD, which is also based on Triode and CRT!), and (4) Lamp Filament.Geissler Discharge tubes were a Victorian novelty. Actual Neons Indicators since about 1910. Neon signs are mostly actually nothing to do with Neon, but coloured Fluorescent Tubes (Mercury Discharge like CFLs and Tubes in a Kitchen), now only the small Neon lamps are made as mains indicators. Magic Eyes from 1934/1935 till late 1960s A kind of miniature CRT (like used in old TV screens). They replaced specialised Neons as tuning indicators within a year. Vacuum Fluorescent Displays (VFDs) are first Calculators from 1967, now widely used in new designs cars, HiFi, DVD/BluRay and Set-box adaptors for Satellite/TV. Actually based also on 1890s CRT but only 25V! For bright daylight operation they are better than LED or LCD, support graphics and custom shapes
- Neon. (90V to 180V strike, 55V to 80V sustain). No filament. (1910 to today, but now only simple annunciator on/off indicator). A disadvantage is the glass goes black with use.
- Seven segment (numbers) or starburst (alphanumeric), Also known as Numatron and Panaflex.
- Nixie (i.e. a shaped letter, digit or symbol for each electrode) Counter/display such as Dekatron.Cold
- Triode type miniature CRT (cathode Ray Tube or Electron Beam) , “Magic Eye”, “Cat’s Eye”. Direct or indirect heated cathode and 90V to 300V operation. Vary negative grid voltage. (1934 to 1965). They have about 1000hrs operational life. They gradually get dimmer.
- Single grid control, but may have multiple moving segments
- Dual controls (i.e. Stereo audio levels) such as older 6AD6 (approximately 6AF6, 6355, R2164) and later EM83 (UM83), EMM801, EMM802,
- Three separately controlled bargraphs. The Octal top view 6AL7 (CV3707) and also side view EMM803.
- Rare electrostatic spot deflection type
- Vacuum Fluorescent Display (VFD) , A little like (2) the “Magic eye” but usually 12V to 30V and many indicators, even multiplexed dot matrix. (1967 to today’s graphics panels)
- Variable Brightness annunciators DM160 (TS6997, CV6094) or IV15
- Single character or digit
- Multiple character multiplexed
- Multiplexed multiple characters and custom annuciators.
- Full graphical displays
- 4. Wire filament 7 segment . (1960s to 1975) Long life lamp filaments, thus orange tinged and high power consumption. Usually 7 segments. Numitrons are in glass valve like envelopes and Minitrons are planar construction.
Links about Numitron and Minitron Filament displays
Numitron (7 segment filament display)
Late model Minitron /Filament 7 segment
LEDs and CRTs here on Radio Museum
CRT Some products such as cash registers used miniature CRTs (TV screens) Other strange CRTs are here at Vintage Technology Association. Some used a shadow mask for each character or up to 16 electron guns! The Telefunken XM1000 See also Charactron at Wikipedia.
Sources of Indicators
The best value Neons, Dekatrons,
Nixie, “Magic Eye”, VFD etc are Russian NOS. Ordinary Neons and larger
VFD are still made. Itron, Futaba , Noritake and possibly Samsung all still supply panels. Numitron and Minitron should be avoided. Check that regular sources are not actually cheaper than eBay!
For Germans, Bargraf, Magisches Auge
and Röhrenradio are respectively “bargraph”, “Magic Eye” and “Valve Radio” (i.e. Vintage or tube Radio). So try searches with those too.
Radio Museum LEDs and CRTs here on Radio Museum
Akh’s Alphanumeric Display page with Nixies, Pixie, VFD, CRT and data. The site calls VFD a “new” display device. Certainly VFD are used in new designs, but date to late 1967 for desk calculators. Possibly nearly 45 years old as I write this.
The Peculiar Parts page
The Little Big Valve page of Ominous Valves
Amazing ‘scope (CRT) vector clocks . Sells Nixes, CRTs, Magic Eyes, but is expensive.
General Display overview at Vintage Calculators
Opto Electronic Devices by Andy Cowley