Difference between revisions of "Lightbulb notes"

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The color/frequency depends on the gas mix, pressure, current, and some other details.
 
The color/frequency depends on the gas mix, pressure, current, and some other details.
 
....and not all are visible directly visible:
 
....and not all are visible directly visible:
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Efficiency:
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Gas-discharge is more electrically efficient than incandescent, but are
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: more complex to manufacture,
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: harder to keep at contant current/light (the [https://en.wikipedia.org/wiki/Electrical_ballast electrical ballast] is used as a current limiter),
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: harder to dim (requires a dimmable ballast)
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Safety, environment:
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You can produce the same light with much less power than if you use incandescent lamps, which is good for overall energy use. (Note that in colder climates, the waste heat of incandescent lamps is useful - it's just shifting around which bill this amount of heating comes from)
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Noble gases are pretty harmless, though not all additions are.
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'''Aging''': The gas atoms slowly eventually embed on the surface of the elctrodes,
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which lowers the pressure (and changes the gas mixure)
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'''Neon glow lamps''' [https://en.wikipedia.org/wiki/Neon_lamp] are a different design gas dischanrge lamp from neon tube lighting, much smaller and historically mostly indicator lights.
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'''Neon glow lamps''' [https://en.wikipedia.org/wiki/Neon_lamp] are a different design gas discharge lamp from neon tube lighting, much smaller and historically mostly indicator lights. The indicator in power strips are typically these{{verify}}.
  
'''Nixie tubes''' are neon glow lamps with multiple specific shapes in one enclosure.
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As they age, they start needing a higher voltage - which in most uses means they start flickering and turn off.
  
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The breakdown characteristics means they can be used for voltage regulation,
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and as overvoltage protection.
  
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They can also be simple photosensors.
  
  
Efficiency:
 
  
Gas-discharge is more electrically efficient than incandescent, but are
 
: more complex to manufacture,
 
: harder to keep at contant current/light (the [https://en.wikipedia.org/wiki/Electrical_ballast electrical ballast] is used as a current limiter),
 
: harder to dim (requires a dimmable ballast)
 
  
  
Safety, environment:
+
'''Nixie tubes''' are cold cathode discharge displays, in a low-pressure neon/mercury/argon.
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{{comment|(and not vacuum tube, nor does it need use thermionic emission. They do share the shape and sockets, because they come from the same era)}}
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A nixue tube has one wire-mesh anode, and a cathodes for each of its specific shapes (usually digits 0 through 9) in one enclosure.
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Being cold-cathode glow discharge (rather than incandescent), they resemble neon glow lamps.
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They predate LCD, LED and VFD, so were a sensible character display method.
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And unpopular once those existed, for a good part because Nixie tubes are more bother: they need over 170V to ignite and ~140V to sustain. They are also current devices so need some management so they don't burn themselves out - they shouldn't pull more than a few mA.
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When displays with large-ish segments have fairly high contrast and a fine grid pattern, they are a '''Vacuum Fluorescent Display''' (VFD) [https://en.wikipedia.org/wiki/Vacuum_fluorescent_display].
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They have a phosphor anode (so resemble CRTs in why they light up), a cathode, and a mesh grid inbetween (so yes, resemble vaccum tube triodes in how it is operated). (See also [https://en.wikipedia.org/wiki/Cathodoluminescence cathodoluminescence])
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They are often flat units, though 7-segment in vacuum-looking tubes are also VFDs.
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They are ~30V devices (order of magnitude), so by modern TTL standards,
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they need somewhat unusual voltages, and a controller.
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These often have a light blueish-green color (sometimes darker, using colored plastic in front), where the color comes from the choice of phosphor. Red, orange, and yellow are also seen.
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VFDs arer seen on microwave clocks (there sometimes just 7-segment), audio gear (where little symbols light up as a whole), and there are also dot matrix variants (e.g. in older cash registers) which works out to be fairly cheap to do since the segments are typically multiplexed anyway.
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In the seventies and eighties VFDs were a sensible and flexible choice - bright enough for lit environments and dimmable to be subtle in the dark; readable from all angles (unlike backlit LCD),
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fine detail and high contrast.
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7-segment is now frequently LED, but not very flexible or small. These days there's also OLED doing fine detail, high contrast, more colors, smaller and less fragile, but VFD is still cheaper than OLED.
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 +
 
  
You can produce the same light with much less power than if you use incandescent lamps, which is good for overall energy use. (Note that in colder climates, the waste heat of incandescent lamps is useful - it's just shifting around which bill this amount of heating comes from)
 
  
Noble gases are pretty harmless, though not all additions are.
 
  
  
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Electroluminescent wire (EL wire) is  
 
Electroluminescent wire (EL wire) is  
 
* a core wire and shield wire
 
* a core wire and shield wire
* a phosphor layer that glows when AC is closeby (due to excited electrons)
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* a phosphor layer that will glows when AC is closeby (due to excited electrons)
 
* a protective layer
 
* a protective layer
 
* often also a colored layer (also further protection)
 
* often also a colored layer (also further protection)

Revision as of 03:52, 13 September 2019

Lightsource types

Technical side

Incandescent

Gas-discharge lamps

LED

Dimming

On ballasts

EL wire

Product side

Lightbulb sockets

Edison screw

Typical for lightbulb/pear shapes. The number is the diameter in mm.

There's quite a few of them, but by far most common are:

  • E26/E27 - common large screw variant
Apparently E26 is for 120V countries and E27 for 230V countries, but they're close enough
  • E14 - common small screw variant

And perhaps

  • E10 - flashlight, bike light
getting less common, because e.g. LED is more efficient than incandescent


There are a handful of other diameters in use (christmast lights, industrial)


See also: http://en.wikipedia.org/wiki/Edison_screw#Fittings

bi-post / bi-pin

This article/section is a stub — probably a pile of half-sorted notes, is not well-checked so may have incorrect bits. (Feel free to ignore, fix, or tell me)

Many of these are IEC 7004.

The number specifies the pin distance. Each distance tends to have a unique socket/plug design, in part to make them more easily identifiable.


Variants with smaller distances are typically small spots (classically halogen), for example:

  • GU10 - pins, 10mm distance, widened bayonet-style end (seems to be one of only a few G variants that has that bayonet)
  • GX5.3 - pins, 5.33mm distance
  • G4 - pins (4mm distance, thinner)

These may be easy to find in supermarkets and such.


Larger variants like G23 and G24 are used in office lighting.



A few further details/associations are specified by the letters, e.g. G, GU, GX, GY, GZ.

For example, GZ bulbs use dichroic glass, which dissipate most of the heat so lets out most of the heat at the back.


Once you get to products, there are more variations, and more is specified, e.g. Power and beam angle can be specified [1].

While endless combinations between socket, bulb, and voltage could exist, there is a lot of consistency in what is actually produced, so in practice most most further details are (only) implied from most specific references being unique(verify).

For example:

  • GU4 are often 12V MR11 bulb
  • GU5.3 are often a 12V MR16 bulb
  • GU10 are often mains-voltage MR16 (as are various others with >7mm pin spacing)
GZ10 is like GU10 but does not have a beveled base, which means you can't use GZ10 in GU10 sockets (but can the other way around). The reason seems to be a heat/safety restriction: GU reduces heat to to the rear/socket, GZ does not.


  • GY6.35, G8, or G9 are more frequently JCD type.
G9 is often mains, G6.35 is often low-voltage



JC, JCD

Refers to a shape - just the small halogen bulbs, no reflector. Can be 12V, 24V, or mains voltage.

Comes in a few base sockets, often one of G6.35, G4, G8(verify)

Apparenly frequently semi-permeable glass, which is why you shouldn't touch it with your oily fingers.


MR, Multifaceted Reflectors

MR (e.g. in MR11, MR16) refers to a Multifaceted Reflector, which produces a more focused beam than simple parabolic reflectors. (see also PAR, which is more specifically an anodized reflector)

MR bulbs are mostly associated with G-style bases, including GU10, GX5.3, and G4.


The number in MRsomething is the bulb diameter - in eighths of an inch, so MR16 bulbs are 5.1cm in diameter, MR11 are 3.5cm.

The combinations of diameter and socket aren't unique - which means it's fairly easy to walk into a store and buy a MR16 and discover you needed one with a GU10 and GU5.3 base and got the other.


You sometimes see specifications of diameter as well as power and beam angle - see [2].



On voltage

Different MR bulbs may be 12V (most) or higher voltage (some), so never blindly assume.


12V may still be AC, though are often DC in practice.(verify) LED-based MR-series often won't care since they need to rectify anyway.

Some of the 12V (switch-mode) adapters designed for a string of halogen MRs will not like the low power draw of LED variants. You need a transformer that is not trying to be clever, one designed for lower draw, attach more lights on a single adapter, or get one designed with LEDs in mind.



Other notes

See also DIY_optics_notes#Stage_lighting.


See also


Other notes

"You shouldn't touch lightbulbs"

Yes, but only really for halogen bulbs.


Devitrification


Hotspots