Is there a conversion or equivilant for a 12 volt,4 watt bulb that I cannot find? All the bulbs now seem to be rated in lumens (eg. 25 lumens). I would like to find one that is the same brightness as the original 4 watt bulb. The 25 lumens about half as bright as the original but I cannot find any bulbs in this size with more lumens ! !
** You need to identify the original bulb correctly, it may be a special type.
For example, Halogen or QI bulbs are brighter than standard ones.
Operating voltage has a big effect too - most so called 12 volt bulbs are rated for automotive use at 14 volts.
Brightness and lifespan are interchangeable, if you apply more volts to a blub it will be brighter but for a shorter time.
....... Phil
The lumen is a measure of visible light output, weighted according to the sensitivity of the human eye, while the Watt is a measure of total power.
The relationship between the two depends upon what proportion of the power is emitted as visible light, and which wavelengths. This depends upon the type of bulb and the voltage (e.g. a 110V, 100W tungsten filament bulb tends to produce more lumens than a similar 240V, 100W bulb).
"Nobrain & nobody TROLL "
** Irrelevant.** So applying more voltage produces less light ???
The simplest bot could do a better job of cribbing drivel like this from Google.
........ Phil
The two units don't convert directly - "lumens" is a measure of the amount of light (specifically, the amount of luminous flux, which is a measure of the perceived power of the light source), while the "watt" measurement only gives the total power dissipated by the bulb (a great deal of which becomes heat, not visible light). You have to know the luminous efficacy of the bulb, or at least the typical efficacy for that technology, to even begin to get from watts to lumens. For instance, incandescent bulbs (which are among the poorest technologies in this regard - they're popular mostly because they're cheap and have a pretty decent color) are typically in the 5-18 lm/W range. A 25 lumen, 4W bulb is just a bit above 6 lm/W, not bad for a low-wattage incandescent but certainly not outstanding either. You could likely do far better, for instance, with an LED "bulb," if you can find one with a compatible base.
Bob M.
When someone asks how to convert between lumens and Watts, the fact they're measuring different things is quite relevant.
Remember that they're both rated at 100W at their specified voltage. This isn't a case of applying 240V to a 110V bulb.
240V bulbs tend to have a lower filament temperature, hence slightly more of the power is emitted as infra-red and less as visible light.
Yes, because the higher voltage bulb has a higher resistance the filament has to be longer and/or thinner, it is therefore mechanically weaker and cannot be run as hot.
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** Was never asked for - f****it. ** YOU are an Gooogling IDIOT
PISS OFF !~!!
....... Phil
FWIW I was perusing light bulbs at the local Home Despot the other day & I noticed, sitting right next to each other, two bulbs, both incandescant, same wattage rating but different lumen ratings- by about 25-30% IIRC.
H.
If they are both standard incandescent lamps, the lower lumen one is a longer life bulb.
-- Service to my country? Been there, Done that, and I\'ve got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida
Was one of them "long-life" or "heavy duty?"
Thanks, Rich
I recall high end photographic slide projectors used to have 24 V bulbs.
Tam
Now that you mention it I do believe that was the case-
H.
Not quite, higher design voltage makes a filament longer and thinner and for a given wattage and life expectancy, the longer thinner filament is less efficient.
- Don Klipstein ( snipped-for-privacy@misty.com)
This is rather common.
All of these factors combined can make quite a difference. A 100 watt
120V 750 hour lamp of a "Big 3" brand and with a coiled-coil filament is typically rated to produce 1710-1750 lumens. A 100 watt 120V 1000 hour off-brand one with a singly coiled multi-supported filament and made by a lower price "lower-than-Big-3-quality" Chinese manufacturer may be rated to produce 1100 lumens.
Various 120-130 volt versions are rated to produce 1560-1730 lumens if designed to last 750 hours.
The small size of the bulb used in a halogen lamp (and also longer life) reduces the economic penalty of using a premium main inert fill gas ingredient. Sylvania appears to me to use krypton rather than argon as the main inert fill gas ingredient in at least some of their "Capsylite" lamps, and their current 100 watt 120V version A19 medium screw base version of those is rated to last 3,000 hours and to produce
1800 lumens. (Sylvania product number 18970, order abbreviation 100A/HAL/F 120V) I remember an older version from the early 1990's claimed to produce 1880 (give or take) lumens and to last 2250 (give or take) hours - I hope I remember correctly! I do remember a different bulb shape - not an "A" bulb shape, but with the wider region consisting of two butt-to-butt truncated cones.- Don Klipstein ( snipped-for-privacy@misty.com)
"Don Klipstein"
** My Q was rhetorical - you fool.
The lumens per watts measures the efficiency of the bulb.
A typical incandescent is around 15 lumens per watt.
Differences arise if a halogen cycle is used or if there are temperature versus lifetime tradeoffs. Or if shaped "effective lumens" rather than real ones are used in sort of an antenna pattern type of thingy.
The latest of LED's are approaching 150 Lumens per watt.
A perfect green bulb would be 700 Lumens per watt. A perfect white one would be half that.
Older tutorial at
-- Many thanks, Don Lancaster voice phone: (928)428-4073 Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552 rss: http://www.tinaja.com/whtnu.xml email: don@tinaja.com Please visit my GURU's LAIR web site at http://www.tinaja.com
In , Don Lancaster wrote in part:
Where can I get one? I thought only laboratory prototypes got that efficient so far. The most efficient LEDs that I am aware of being in production and on the market achieve about 80 lumens/watt.
683 by definition for 540 THz, approx. 555 nm.Depends on what you call white. If the "white light" is equal power per unit wavelength from 400 to 700 nm, then light source that is 100% efficient at producing such light and nothing outside the 400-700 nm range would achieve 243 lumens per watt.
However, other forms of "white light" can get higher. A perfectly 100% efficient light source producing a mixture of 576 nm yellow and 450 nm blue to approximate the color of 3500K would achieve 495 lumens per watt.
- Don Klipstein ( snipped-for-privacy@misty.com)
The LED trade journal is full of high efficiency leds.
one of our banner advertisers is an industry insider with special efficiency expertise ...
-- Many thanks, Don Lancaster voice phone: (928)428-4073 Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552 rss: http://www.tinaja.com/whtnu.xml email: don@tinaja.com Please visit my GURU\'s LAIR web site at http://www.tinaja.com
Thanks!
Meanwhile, I do frequently check into
- Don Klipstein ( snipped-for-privacy@misty.com)
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