Difference between revisions of "Lightbulb notes"

From Helpful
Jump to: navigation, search
m
m (Lightbulb sockets)
Line 409: Line 409:
 
* http://commons.wikimedia.org/wiki/Compact_fluorescent_lamp
 
* http://commons.wikimedia.org/wiki/Compact_fluorescent_lamp
 
* http://www.besthomesystems.com/learn/lighting_step4.html
 
* http://www.besthomesystems.com/learn/lighting_step4.html
 +
 +
 +
=Other notes=
 +
 +
=="You shouldn't touch lightbulbs"==
 +
 +
Yes, but only really for halogen bulbs.
 +
 +
 +
 +
'''Devitrification'''
 +
 +
<!--
 +
The main reason is devitrification.
 +
 +
For reference, vitreous means glass-like, here referring to a random rather than crystalline structure (applies to anything that you can get to do both, including water[https://en.wikipedia.org/wiki/Amorphous_ice]).
 +
 +
Devitrification means something glassy returns to a more crystalline form.
 +
This happens more easily with higher temperatures, and/or when there is a nucleation center for a crystalline structure to start growing.
 +
 +
Devitrification of clean quartz usually only happens noticeably above 1200 °C (in most typical glasses it's around 1400 °C{{verify}}), but with surface impurities can start happening below 1000 °C.
 +
 +
 +
Because of crystal properties, it will look cloudier.
 +
Which in high powered lightbulbs is just not useful.
 +
 +
 +
 +
In the realm of lightbulbs, this mostly applies to halogen bulbs, because they're likely to be quartz.
 +
{{comment|(not all halogen bulbs uses quartz, as some don't need to. But unless you can reliably tell, it's good habit / rule of thumb to not touch anything that looks halogen-bulby)}}
 +
 +
 +
The choice of quartz over glass in these bulbs seems to mainly be that quartz is stronger, meaning it can deal with higher pressure, higher temperature, and therefore makes sense for brighter incandescent bulbs -- which in (particularly consumer) practice mostly describes halogen bulbs.
 +
 +
The issue is that quartz can devitrify much more easily than regular glass - for a large part ''because'' they run hotter (mostly because halogen bulb's halogen cycle only works above ~250 °C) - on the order of 500 °C, while incandescent is usually on the order of 150 °C.
 +
 +
 +
That said, devitrification barely affects bulb life.
 +
 +
 +
Apparently applies less to a lot of professional high-powered lighting, in that much of that uses hardglass.
 +
 +
 +
 +
http://www.conservation-wiki.com/wiki/Devitrification
 +
 +
https://highlyeducatedti.com/blogs/information/69786883-first-post
 +
 +
https://en.wikipedia.org/wiki/Halogen_lamp#Halogen_cycle
 +
 +
-->
 +
 +
'''Hotspots'''
 +
 +
<!--
 +
The other reason you hear is that they could create hot spots.
 +
 +
It's true that a temperature differential can break glass - this is e.g. why some drinking glasses shouldn't be used for tea.
 +
 +
If something would stay on the surface, it would set up a temperature differential and probably cause this -- a little easier on halogen because they are hotter.
 +
Yet a little oil, if it doesn't do this fairly soon, will often mean it burn and sputter off soon enough.{{verify}}
 +
 +
 +
-->

Revision as of 21:10, 12 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