Thanks, Jim, for yet another one of your cogent digests of the state of the
art!
Dan Weeks
75 Argosy 26
(stock lighting + a flourescent)
> From: Jim Dunmyer <[EMAIL PROTECTED]>
> Reply-To: [EMAIL PROTECTED]
> Date: Tue, 24 Apr 2001 19:55:26 -0400
> To: Multiple recipients of VACList <[EMAIL PROTECTED]>
> Subject: [VAC] Re: LEDs
>
> David,
> From the pioneer.net link:
> ------------------------------------------------------------------------------
> ---------------------------
>
> 7. Are LEDs more efficient than other light sources such as incandescent
> and fluorescent types?
>
> LEDs are used more and more as incandescent light replacements. Their
> are at least 4 possible advantages to
> using LEDs compared to incandescent sources: a) longer lifetime, i.e.,
> years rather than months of service, b)
> power savings in some applications (more on this later), c) reduced heat
> output in some applications, and d)
> deep saturated hue (color) of output without filters.
>
> Does this mean that LEDs are generally more efficient, that is, can they
> be used to save power? With the
> current state of the art, incandescent bulbs actually put our more
> visible light per watt than most LEDs. So, if you
> want white light or if you don't care about color of illumination,
> incandescents are somewhat more efficient than
> any combination of LEDs, and they remain more efficient than the newest
> 'white LEDs'. However, if you want
> single color illumination, LEDs can be much more efficient, since, in
> that case, much of the light output of the
> incandescent source is absorbed by a filtering system. If we include
> fluorescent fixtures, here is the general
> picture of light source efficiency:
>
> 1) As of today, fluorescent fixtures remain the clear winner in terms of
> output in lumens/watt. Halogen
> incandescents are second. LEDs are third.
>
> 2) LEDs win the race if what you want is light of a single color
> available from efficient LEDs. The losses involved
> in filtering fluorescents and incandescents are such that LEDs win out
> here. Examples include stoplights and
> auto taillights.
>
> 3) LEDs provide the longest lifetime by far.
>
> 4) If your supply is some low DC voltage, driving circuits for LEDs are
> extremely simple and cheap compared to
> same for fluorescents.
>
> 5) White LEDs, although they do not presently provide as many
> lumens/watt as incandescent bulbs, can be
> useful because of the long life and low heat output.
>
> Don Klipstein has done some lumen efficiency tests of LEDs. See the
> Links section.
>
> For reference, fluorescent fixtures put out about 30 lumens per watt.
> Incandescent bulbs put out about 8 lumens
> per watt.
>
> In summary, if I were equipping a remote cabin with lighting, I'd be
> using low voltage fluorescent fixtures at this
> point in time.
> ------------------------------------------------------------------------------
> ---------------------------
>
> <<Jim>>
>
>
> David Sawicki wrote:
>>
>> Take a look at the following websites for more info on LEDs:
>>
>> http://www.pioneernet.net/optoeng/LED_FAQ.html
>>
>> http://ledmuseum.home.att.net/reserved.htm
>>
>> Some of the material is not really pertinent to Airstream lighting, but the
>> sites are helpful for basic understanding.
>>
>> Dave Sawicki
>> '69 Caravel
>
> --
>
> <<http://www.oldengine.org/members/jdunmyer>>
> <<[EMAIL PROTECTED]>>
> <<lower SE Michigan, USA>>
> <<mailto:[EMAIL PROTECTED]>>
>
>
>
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