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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] | ||
|- | |- | ||
| 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 | ||
|} | |} | ||
''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]] | ||