Indicators: Gas Filled, Neon, Argon
Types of Neon Indicator and other Gas Discharge Indicator
- Static indicator, on/off only
- Rare and poor operation Rod tuning (Tuneon) indicator. Tuneon 3184 by Cossor, similar 3180 & 4662, Flash-O-Graph, Tune-A-Lite, Tone-Beam. These are from 1931 till 1934/1935 when the first true "Magic Eye" 6E6 appeared.
- The extremely rare VG1 annular neon tuning indicator. (identical to the Visi-glow) 1934
- Bargraph such as Russian IN-9(12mA),and IN-13 (4mA=FSD)
- Counting type indicator (Dekatron)
- Formed characters (US Nixie 1955 and Russian copies)
- Segment Numeric or Alphanumeric (seven Segment, Starburst, Planoplex)
- Dot matirx (Plasma Monitors and small indicators like ITM2M as well as single characters)
- Unusual Electoluminescent Quartz or Leuchtquartz, a crystal resonator that also includes Neon (Article in German and English)
Neon was discovered in 1898 by William Ramsey. The first commercial neon lamps were made about 1910. But in the late 19th Century there was much experimention with low pressure gas discharge and different gasses with many ornamental lamps made such as the example on the right (from a Victorian painting as colour photography was very rare).
Neon and other gases need a particular voltage to be reached before ANY current flows. This is the "striking" voltage. The voltage will then try to drop to a constant lower value depending on gas and to an extent construction. For this reason a gas discharge tube has a negative resistance and must have a series resistor to limit current. Below a certain current the discharge will stop and the indicator go out. The voltage above this point is the sustaining voltage.
Basic Neon Indicator or "Annunciator"
This property of neons is used for combination counter/display such as the Dekatron and also as Releaxation Oscillators and Capacitor Leakage testers.
The Strike voltage is lowered by light, radiation, RF fields, UV or a third electrode. The cold cathode thyratron uses a trigger wire to initiate the "Turning on" much like a Unijunction transistor or Thyristor. However even miniature Thyratrons the size of small neons are not commonly used as indicators.
Larger bulbs with Cross or flame shaped elements are still manufatured. In the past a wide range of neon lamp shapes were produced.
Today (2011) the Plasma Panel is on wane for domestic video as the LCD are now as good if not better and cheaper to make.
Even the humble Neon Indicator for mains is often now replaced by LED, though some new products still have neon on/off indicators (annunciators).
Broadcasting to the Public started in about 1921 and Neon signs sold in the USA from about 1923. However it wsa more widespread use of the Superhet radio that Manufacturers wanted a "tuning indicator"
1931 to 1935 Neon Tuning rods
Demo by Joe Sousa
- Duovac Radio Tune-A-Lite Read the Article
- Atwater Kent Tonebeam
- GEC Tuneon
- Flash-O-Graph (in Fada Radios)
- Philips 4662
- Cossor 3180
- Cossor 3184
Two Tuneon tubes owned by a friend. Note how black glass has turned.
There is a suggestion that these didn't work very well. With usage the glass all neon tubes will go black. The rare VG1 annular neon tuning indicator. (identical to the Visi-glow) 1934 is more a "Magic Eye" shape. The true (and effective) "Magic Eye" (A miniature beam deflected CRT type triode) was developed in 1934 and common by 1935.
The year of introduction and year ceased production is unknown. The IN-9 is two wire, smaller and less sensitive. The IN-13 has a third "trigger" or "pilot" wire to enable strike at a lower HT than would otherwise be the case. They are available in Neon (pinky/orange) or Argon (purple/violet).
IN-9 10mA is about 100mm. Max is 12mA
The bargraph length is proportional to current. They use rather too much power for battery equipment.
The larger but more sensitive IN-13, FSD is 4mA
With use the bargraph glass will blacken from bombardment with Neon or Argon ions.
Dekatrons, Nixies and other Numeric Neon based displays.
Read also these related articles
- The History of Tuning Indicators
- How the German Tuning indicators work
- Magic Eye Patterns
- Vintage Indicators, excluding Mechanical
- IN-13 for Signal Strength
The early Nixie displays were made by a small vacuum tube manufacturer called Haydu Brothers Laboratories, and introduced in 1955 by Burroughs Corporation, who purchased Haydu and owned the name Nixie as a trademark. Nixie tubes used an entire shaped character for each digit or letter to be displayed.
Many Burroughs and other US Nixie tubes are available as NOS (New Old Stock). The Russians appear to have copied many US types and created others. Some Russian Nixies use a copy of the "5" flipped upside done as the "2". Russian stock may be newer NOS. Beware of ex-equipment Nixies for Restoration, Repair or new projects as the glass blackens. Another problem is more than one digit on at the same time. This is alleged to be caused by "swarf" in the tube, but a gentle tap or shake can sometimes cure it whatever the real reason is.
|ins-1||Annunciator||End dot (e.g. Decimal point)|
|in-1||Numerals||18||End view Nixie|
|in-2||Numerals||End view Nixie (pins)|
|in-3||Annunciator||Side dot (e.g. Decimal point)|
|in-4||Numerals||End view Nixie (pins)|
|in-7||Symbols||End view n + m A V M O ~ K —|
|in-7a||Symbols||End view n K - m % + M|
|in-7b||Symbols||End view W V Hz S|
|in-8||Numerals||End view Nixie (pins)|
|in-8-2||Numerals||End view Nixie (wire)|
|in-12a||Numerals||End view (pins)|
|in-12b||Numerals||End view (wire)|
|in-13||Bargraph||4mA with Pilot (wire)|
|in-15a||Symbols||W F Hz S H Ω A|
|in-17||Numerals||10||Miniature Nixie (wire)|
|in-19a||Symbols||Nixie p, n, m, µ, k, M, %, °C|
|in-19b||Symbols||?, Hz, F, H, V, S, T, Ω|
|in-19v||Symbols||Nixie + - A/B _ < % Π dB|
|in-22||Numerals||End view Nixie (wire)|
|in-24||Annunciator||short bar "Fuse style"|
Russian parts usually are marked in Cyrillic so
in-19a is marked ИН-19А
in-19b is marked ИН-19Б
in-19v is marked ИН-19B
ins-1 might be in bag / box if bulk as ИНС-1
(Transliteration of cyrillic often represented by using lower case)
|mth90||Annunciator||1 dot||Thyratron: Wires pre-cut with balls of solder|
|th5b (ТХ5Б)||Annunciator||1 dot||Thyratron|
|its1a||7 Segment||1 digit||Thyratron: -300VDC, 100VDC, and 50VDC but 5V control. Looks like VFD due to green phosphor. Self-latching|
|itm2m||Annunciator||4 x 4||Thyratron: Coloured Matrix|
|in-28||Lamp||1 dot|| building large dot matrix. Very bright
31 mm, 13ma @ 175V
(Images edited and processed from larger photographs of Ukrainian sellers of NOS,
so "fair use" for illustrative & comparison purposes)
(with AC, DC only one rod is lit)
There are some articles in German. Perhaps the bar varies in length with current due to a slight angle of the electrodes. A minimum current is required so there is usually an adjustment potentiometer.
Suggestion by Prof. Dr.-Ing. Dietmar Rudolph.