Neon Lamps: Difference between revisions
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If the neon lamps fail, the CRT grid voltage will be affected. | If the neon lamps fail, the CRT grid voltage will be affected. | ||
Another common use is for DC bias shifting, e.g. in 500-series timebase circuits. | Another common use is for DC bias shifting, e.g. in 500-series timebase circuits. In such circuits, a 56 V Zener diode may be a possible replacement for the neon. | ||
[[File:Neons in 545 timebase circuit.jpg|200px]] | [[File:Neons in 545 timebase circuit.jpg|200px]] | ||
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|align="center"| 58 (46-78) V | |align="center"| 58 (46-78) V | ||
|align="center"| 0.6 mA | |align="center"| 0.6 mA | ||
| short length, formed tip for end-on viewing | | short length, formed tip for end-on viewing; dark compensated; =~ modern type [https://eu.mouser.com/ProductDetail/VCC/A2B?qs=%252BE2FUV3Ulmz0JmjQi2dc2Q%3D%3D A2B] | ||
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| NE-23 | | NE-23 | ||
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|align="center"| 59 V | |align="center"| 59 V | ||
|align="center"| 0.3 mA | |align="center"| 0.3 mA | ||
| | | dark compensated | ||
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''Please add'' | ''Please add'' | ||
===Dark compensation=== | |||
Neon lamps require a higher voltage to ignite if operated in total dark, this is known as ''Dark effect''. | |||
This was compensated in some types by a "mild radioactive additive" to help with ionization, typically a small amount of Krypton-85 (beta emitter, 10.8 years half life) added to the gas filling. | |||
After 50 years, radiation from this source will have reduced to ~3% of the intensity at new. Modern NE-2 variants will likely not contain such an additive in the first place. | |||
[[Category:Repair issues]] | [[Category:Repair issues]] | ||
[[Category:Gas discharge tubes]] | [[Category:Gas discharge tubes]] | ||
Revision as of 04:03, 6 June 2023
Neon lamps are used for at least three different things in Tek instruments:
- Indicator lamps, e.g., for power, beam position, uncalibrated status, or a decimal point
- Voltage clamp, similar to how a zener diode is used
- In relaxation oscillators, e.g. in 7000-series power supplies
Neon lamps fail more than most other components. A common failure mode is for the leads to break off, often close to the glass bulb, due to corrosion and vibration. Another failure mode is for the I-V characteristic to drift.
Neon lamps are used as a voltage clamp in the CRT circuit for setting the CRT grid voltage in many Tek instruments. A typical example is seen in the 561A:
If the neon lamps fail, the CRT grid voltage will be affected.
Another common use is for DC bias shifting, e.g. in 500-series timebase circuits. In such circuits, a 56 V Zener diode may be a possible replacement for the neon.
When in doubt, replace the neon lamps. In a pinch, it may be possible to reattach broken leads after careful grinding of the glass.
See also
- Neon lamp @ Wikipedia
- GE Glow Lamp Manual, 2nd Ed. 1965
- William G. Miller, Using and Understanding Miniature Neon Lamps (1969)
- Nixie tubes
- Voltage regulator tubes
Types and data
| Type | Tek P/N | Voltage | Current | Notes | |
|---|---|---|---|---|---|
| Ignition | Operating | Nominal | |||
| NE-2 | 150-002 | 76 (60−90) V | 58 V | 0.3 mA | =~ modern type A1A |
| NE-2V | 150-030 | 76 (60−90) V | 58 (46-78) V | 0.6 mA | short length, formed tip for end-on viewing; dark compensated; =~ modern type A2B |
| NE-23 | 150-027 | 74 (60−90) V | 59 V | 0.3 mA | dark compensated |
Please add
Dark compensation
Neon lamps require a higher voltage to ignite if operated in total dark, this is known as Dark effect. This was compensated in some types by a "mild radioactive additive" to help with ionization, typically a small amount of Krypton-85 (beta emitter, 10.8 years half life) added to the gas filling.
After 50 years, radiation from this source will have reduced to ~3% of the intensity at new. Modern NE-2 variants will likely not contain such an additive in the first place.