Difference between revisions of "Lightbulb notes"

From Helpful
Jump to: navigation, search
m (EL wire)
m (VFDs)
(4 intermediate revisions by the same user not shown)
Line 4: Line 4:
  
 
==Technical side==
 
==Technical side==
 +
 +
===Arc lamp===
 +
<!--
 +
{{stub}}
 +
 +
The first electric lighting was the carbon arc lamps.
 +
They were moderately practical for larger area lighting (e.g. streets, buildings) since early 1800s,
 +
well before commercial incandescent (early 1900s).
 +
 +
 +
From today's perspective, they were basically welding machines used for their light: two carbon rods in air, which due to the fact that they are ionizing to the point of plasma means they produces a continuous flame as well.
 +
 +
This was e.g. how early searchlights, lights on movie sets, and movie projectors worked.
 +
 +
It also wasn't the most safe (fire, produces all UV variants, carbon monoxide), efficient, or practical (needs startup, adjustment, noisy, creates RFI), which is why in most uses they were replaced by either incandescent, or refined forms of arc lights.
 +
 +
 +
Those refinements include mercury vapor lamps, sodium lamps and fluorescent lamps, and some offshoots.
 +
Which is why today, 'arc lamp' often refers to these different gas discharge types (which do not elicit plasma).
 +
 +
High Intensity Discharge refers to arc lamps when categorized under the gas discharge umbrella.{{verify}}
 +
 +
 +
 +
The gas discharge is a refinement of what's happening.
 +
Due to inert gases and lower pressure, you still get ionization, but instead of focusing on creating plasma,
 +
you let the mass of electrons ionizing the gas do the work.
 +
 +
Various gas-discharge may still use an arc at startup (called striking),
 +
but most will then only sustain the electron flow,
 +
and count on electrons ionizing gases to produce light.
 +
 +
 +
 +
 +
"In ''most'' uses", because there are still arc lamps around, they just tend to be specific.
 +
 +
As arc lights are neither subtle or efficient,
 +
they tend to be used where you want a small spot of light,
 +
and/or the wide, white-looking color spectrum.
 +
 +
For example:
 +
 +
* xenon short-arc lamp, e.g. the large ones used in IMAX (and smaller ones in random other places).
 +
: light source is plasma - but a very small point of it, and with a large anode because it also has to act as a heatsink.
 +
 +
* xenon long-arc lamp [https://en.wikipedia.org/wiki/Xenon_arc_lamp#Xenon_long-arc-lamps]
 +
: often used for xenon's wide color spectrum
 +
: but not very efficient
 +
: this is e.g. fine in photography
 +
: This is mostly done for the wide color spectrum of xenon
 +
 +
* xenon referring to automotive headlamps are really metal-halide lamps in regular operation
 +
: ...but because that takes ~20 seconds to become bright, that first time is bridged by xenon arc light
 +
 +
 +
-->
 +
 +
 
===Incandescent===
 
===Incandescent===
 
<!--
 
<!--
  
Incandescent lamps have a low-resistance wire that,
+
Incandescent lamps are a low-resistance wire that,
with enough voltage,
+
with enough voltage, becomes hot enough to radiate EM in the visible spectrum.
becomes hot enough to radiate EM in the visible spectrum.
+
  
  
In air, the filament oxidation would happen much too quickly due to, well, the oxygen.
+
In air, the filament would oxidize much too quickly and burn out.
  
Vacuum inside works, and makes for a well controlled evaporation, but it turns out that evaporation is faster than necessary.
+
Putting the filament in a vacuum tube makes for controlled evaporation,
 +
but it turns out that evaporation is faster than necessary.
  
Regular indandescent lamps have an inert gas, typically argon (and some nitrogen to help avoid arcing), as this makes for slower evaporation of the filament than in a vacuum.
+
Regular indandescent lamps have an inert gas, typically argon (and some nitrogen to help avoid arcing),
 +
as this makes for slower evaporation of the filament than in a vacuum.
 
This also lets it run at higher temperatures for more light and/or lifetime for otherwise the same design.
 
This also lets it run at higher temperatures for more light and/or lifetime for otherwise the same design.
  
{{comment|(Krypton and xenon have better isolation than argon, but are pricier, so are only used for designs that need it)}}
+
{{comment|(Krypton and xenon isolation better than argon, but are pricier, so are only used for designs that need it)}}
  
  
'''Halogen lamps''' are a variant that adds a halogen gas, which last longer due to a [https://en.wikipedia.org/wiki/Halogen_lamp#Halogen_cycle halogen cycle] redepositing some of the metal back onto the filament (also needs to be hotter for this to work).
 
  
 +
'''Halogen lamps''' refer to the [https://en.wikipedia.org/wiki/Halogen_lamp#Halogen_cycle halogen cycle] redepositing some of the freed filament metal back onto the filament. This requires a halogen gas,
 +
and for the bulb to burn about twice as hot as most incandescent.
 +
This makes sense for lights that typically want to be bright.
  
  
Incandescent is generally inefficient in that most of the energy they consume is actually emitted in the IR spectrum, i.e.  as heat. While in cold climates this is helps electrically heat your house, in general it's a waste product.
 
  
 +
Incandescent is inefficient in that they are so wide spectrum that, when you want a lot of it in the visible spectrum, you also similar amounts of power emitted in near infrared, i.e. as heat.
  
Dimming incandescent bulbs extends its lifetime due to slower evaporation of the filament.
+
While in cold climates this helps electrically heat your house, in general it's a waste product that is avoidable.
Dimming halogen lamps means ''less'' lifetime when you stop the halogen cycle, which you would when dimming {{comment|(due to logarithmic-ish brightness-for-power)}}.
+
 
 +
 
 +
 
 +
Dimming incandescent bulbs extends their lifetime due to slower evaporation of the filament.
 +
 
 +
Dimming halogen lamps means ''less'' lifetime, at least when you stop the halogen cycle, which you do very easily {{comment|(due to logarithmic-ish brightness-for-power)}}.
  
  
Line 46: Line 113:
  
  
What they share is that they constantly ionize gas via electric discharge,
+
What they share is that they sustain ionization of gas via electric discharge.
which emits photons as that gases loses its electrons.
+
Ionized gas means almost-free movement of electronss, which when they hit the present gas causes photon emission.  
  
  
The gas is often one or more noble gases, and may include things like like mercury, sodium,  
+
Compare this to incandescent, which heats a filament basically for its radiation which, being a black body style thing, is wide-band which is often wasteful.
and metal halides vaporized during startup to become part of the gas mixture.
+
  
The color/frequency depends on the gas mix, pressure, current, and some other details.
 
....and not all are visible directly visible:
 
  
  
 +
The gas is often one or more noble gases (and frequently a Penning mixture, for reasons of efficiency),
 +
and may include things like like mercury, sodium, and metal halides (vaporized during startup to become part of the gas mixture).
 +
 +
The color/frequency depends on the gas mix, pressure, current, and some other details.
 +
....and not all are visible directly visible:
  
  
 
Efficiency:
 
Efficiency:
  
Gas-discharge is more electrically efficient than incandescent, but are
+
Gas-discharge is more electrically efficient than incandescent, but
: more complex to manufacture,  
+
: 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),  
+
: are 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)
+
: are harder to dim (requires a dimmable ballast)
  
  
 
Safety, environment:
 
Safety, environment:
  
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)
+
Gas discharge can produce more light than incandescent using the same power, so is a step better for overall energy use {{comment|(Note that in colder climates, indoor use 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.
 
Noble gases are pretty harmless, though not all additions are.
  
  
'''Aging''': The gas atoms slowly eventually embed on the surface of the elctrodes,
+
'''Aging''':
 +
 
 +
The gas atoms slowly eventually embed on the surface of the electrodes,
 
which lowers the pressure (and changes the gas mixure)
 
which lowers the pressure (and changes the gas mixure)
  
 
+
-->
 
+
====Fluorescent lamps====
 +
<!--
  
 
'''Fluorescent lamps'''[https://en.wikipedia.org/wiki/Fluorescent_lamp] are those variants that mostly emit UV, which hits a fluorescent coating inside the same tube that absorbs (so blocks) the UV and lights up in the visible range. The filament's coating is what wears out {{comment|(the blackened bits of tube on each end are mostly that metal)}}
 
'''Fluorescent lamps'''[https://en.wikipedia.org/wiki/Fluorescent_lamp] are those variants that mostly emit UV, which hits a fluorescent coating inside the same tube that absorbs (so blocks) the UV and lights up in the visible range. The filament's coating is what wears out {{comment|(the blackened bits of tube on each end are mostly that metal)}}
Line 91: Line 163:
 
'''Compact Fluorescent Lighting''' ('''CFL''')[https://en.wikipedia.org/wiki/Compact_fluorescent_lamp] are a more compact version of the older-style tubes, designed to replace incandescent lightbulbs: Edison-screw, small ballast, tube folded into a smaller area.
 
'''Compact Fluorescent Lighting''' ('''CFL''')[https://en.wikipedia.org/wiki/Compact_fluorescent_lamp] are a more compact version of the older-style tubes, designed to replace incandescent lightbulbs: Edison-screw, small ballast, tube folded into a smaller area.
  
 
+
-->
 +
====Mercury and sodium vapor lamp====
 +
<!--
 
A '''mercury-vapor lamp''' is a gas discharge lamp that puts an arc though vaporized mercury.  
 
A '''mercury-vapor lamp''' is a gas discharge lamp that puts an arc though vaporized mercury.  
 
They are more energy-efficient than most fluorescent lights, and have a longer lifetime,
 
They are more energy-efficient than most fluorescent lights, and have a longer lifetime,
Line 101: Line 175:
 
Both are yellowish, the low-pressure variant more so.  
 
Both are yellowish, the low-pressure variant more so.  
  
 +
-->
 +
====Metal halide lamp====
 +
<!--
 
'''Metal-halide lamp'''[https://en.wikipedia.org/wiki/Metal-halide_lamp] are also very similar to mercury-vapor lamps.  
 
'''Metal-halide lamp'''[https://en.wikipedia.org/wiki/Metal-halide_lamp] are also very similar to mercury-vapor lamps.  
 
They are used in car headlights, photographic lighting, stage lighting.
 
They are used in car headlights, photographic lighting, stage lighting.
  
  
 +
-->
  
  
Hot cathode refers to designs that heats the cathode to get [https://en.wikipedia.org/wiki/Thermionic_emission thermionic emission], including most fluorescent lamps, vacuum tubes, and electron guns (as e.g. in CRTs and electron microscopes).
+
====Neon glow lamps====
 
+
<!--
 +
'''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.
 +
Seen e.g. in  
 +
: power strips indicators {{verify}}.
  
'''Cold cathode''' designs[https://en.wikipedia.org/wiki/Cold_cathode] (note: still be too hot for your fingers, think 200C versus 700C) are functioning below their thermionic emission threshold, instead freeing the electrons purely because of the voltage between the electrodes.
+
As they age, they start needing a higher voltage - which in most uses means they start flickering and turn off.
  
Cold-cathode tends to last longer (because it doesn't rely on filament coating{{verify}}),
 
but working at higher voltages makes it less efficient particularly for smaller tubes,
 
and need an additional conversion.
 
 
Cold-cathode applications include
 
: '''Neon tube lighting''' refers to cold-cathode gas-discharge setup, mostly to those with long tubes, low pressure, and high voltage.
 
: some not-as-common discharge-tube / fluorescent designs
 
: some types of vacuum tube
 
: monitor backlights were CCFL for a good while due of their lifetime, though LED is a little more efficient per power so is now also common.
 
 
 
 
'''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}}.
 
 
As they age, they start needing a higher voltage - which in most uses means they start flickering and turn off.
 
  
 
The breakdown characteristics means they can be used for voltage regulation,
 
The breakdown characteristics means they can be used for voltage regulation,
Line 132: Line 198:
  
 
They can also be simple photosensors.
 
They can also be simple photosensors.
 +
-->
  
 +
====Nixie tubes====
  
 
+
<!--
 
+
 
+
 
'''Nixie tubes''' are cold cathode discharge displays, in a low-pressure neon/mercury/argon.
 
'''Nixie tubes''' are cold cathode discharge displays, in a low-pressure neon/mercury/argon.
 
{{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)}}
 
{{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)}}
Line 142: Line 208:
 
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.
 
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.
 
Being cold-cathode glow discharge (rather than incandescent), they resemble neon glow lamps.
 
Being cold-cathode glow discharge (rather than incandescent), they resemble neon glow lamps.
 
They predate LCD, LED and VFD, so were a sensible character display method.
 
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.
 
  
  
 +
They were once a very sensible character display method, as they predate VFD, LCD, and LED.
  
 +
Also 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.
  
 +
-->
  
 +
====VFDs====
 +
<!--
 
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].  
 
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].  
  
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])
+
They have a phosphor-coated anode (so resemble CRTs in why they light up), a cathode to generate electrons, and a mesh grid inbetween to switch them (so yes, resemble [[vaccum tube]] triodes in how it is operated).
 +
(See also [https://en.wikipedia.org/wiki/Cathodoluminescence cathodoluminescence])
  
 
They are often flat units, though 7-segment in vacuum-looking tubes are also VFDs.
 
They are often flat units, though 7-segment in vacuum-looking tubes are also VFDs.
Line 166: Line 235:
  
 
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.
 
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.
 +
-->
 +
 +
====Further notes====
 +
<!--
 +
 +
Hot cathode refers to designs that heats the cathode to get [https://en.wikipedia.org/wiki/Thermionic_emission thermionic emission], including
 +
most fluorescent lamps{{verify}},
 +
[[vacuum tubes]], and
 +
electron guns (as e.g. in CRTs and electron microscopes).
 +
 +
 +
'''Cold cathode''' designs[https://en.wikipedia.org/wiki/Cold_cathode] (note: still be too hot for your fingers, think 200C versus 700C) are functioning below their thermionic emission threshold, instead freeing the electrons purely because of the voltage between the electrodes.
 +
 +
Cold-cathode applications include
 +
: '''Neon tube lighting''' refers to cold-cathode gas-discharge setup, mostly to those with long tubes, low pressure, and high voltage.
 +
: some not-as-common discharge-tube / fluorescent designs
 +
: nixie tubes
 +
: monitor backlights were CCFL for a good while due of their lifetime, though LED is a little more efficient per power so is now also common.
 +
 +
 +
Cold-cathode tends to last longer,
 +
in part because of heat management,
 +
in part because some hot cathode relies on filament coating which will leave,
 +
but working at higher voltages makes it less efficient particularly for smaller tubes,
 +
and need an additional conversion.
  
  

Revision as of 19:02, 13 September 2019

Lightsource types

Technical side

Arc lamp

Incandescent

Gas-discharge lamps

Fluorescent lamps

Mercury and sodium vapor lamp

Metal halide lamp

Neon glow lamps

Nixie tubes

VFDs

Further notes

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