RE: Re: White LED Lighting... was RE: Re: ADSL vs Cable

["i.bird@xxxxxxx" <Ian@xxxxxxx>]

Quite right and exactly as my pathway lights are done. For those that have
missed it look at www.mollyology.com and then projects. If anyone wants
more information than I have provided then please ask.

Individual LED's will draw different amounts of current due to their not
being exactly the same and some other factors. If say each dropped 1.2
volts in theory and you put 5 in series and supplied it 7.2 volts (5 times
1.2) then all should be well. In reality one or more of the LED's would
draw more current which would make it brighter in relation to the others At
worse it would die and they would all stop working.

Ian B

Original Message:
-----------------
From: Frank Mc Alinden armagh@xxxxxxx
Date: Wed, 24 Apr 2002 21:30:41 +1000
To: ukha_d@xxxxxxx
Subject: Re: White LED Lighting... was RE: [ukha_d] Re: ADSL vs Cable


Personally i would use 12vdc bus to power them and use current limiting
resistors for each Led . The  resistor value  would be approx 450
ohm (470). It was calculated as follows
the led voltage = 3v approx so 9v must be dropped  across the resistor
. The current = 20mA  divide voltage (9V) by .02
and hopefully the answer is 450 otherwise ive just made a fool of myself
.Leds should not be connected in parallel without individual resistors as
one robs the other of current . 
Frank Mc
  ----- Original Message ----- 
  From: Ian Lowe 
  To: ukha_d@xxxxxxx 
  Sent: Wednesday, April 24, 2002 9:13 PM
  Subject: RE: White LED Lighting... was RE: [ukha_d] Re: ADSL vs
Cable


  Straight off, these can't be dimmed by X-10 in the way you mean
Nikola, as
  they are not 240v replacements.. they are simple components,
reqiring a 3V
  supply. It seems you wire them in serial/parallel networks to
provide a 12V
  system, which can then be used in a system similar to existing 12v
Halogens.

  The devices themselves vary their light output dependant on current,
so they
  can be dimmed quite easily, you just need a bit of circuitry to do
so.. (or
  possibly, a dimmable transformer would do the trick.. my
leccytronics isn't
  good enough to be sure)

  Ian.

  -----Original Message-----
  From: Nikola Kasic [mailto:nikola@xxxxxxx]
  Sent: 24 April 2002 11:47
  To: ukha_d@xxxxxxx
  Subject: RE: White LED Lighting... was RE: [ukha_d] Re: ADSL vs
Cable


  I might be interested, but I'm not sure.
  Can you tell me can they be dimmed using some kind of X10
dimmer?
  I'm looking for some lighting solution for my hallway. I want to
put
  recessed lights because utility room doors ara just 2-3 cm below the
ceiling
  and they hit the current light unit and broke it. But my problem is
that my
  suspended ceiling (plasterboard) is just 5 cm from concrete ceiling.
That's
  not enough for putting any halogen light, because of the heat. That
area is
  not ventilated, of course, it's just a plasterboard screwed onto
wooden
  battens.
  Could this be a solution then?
  Nik
  -----Original Message-----
  From: Ian Lowe [mailto:ian@xxxxxxx]
  Sent: 24 April 2002 10:00
  To: ukha_d@xxxxxxx
  Subject: RE: White LED Lighting... was RE: [ukha_d] Re: ADSL vs
Cable


  yeah,

  I found a company in korea doing MR14 MR16 sized replacements for
the small
  Lv Halogens, in 20W equivelants. These were clusters of 15 LEDs,
each
  producing about 3Cd..

  Since digging more and more, I found a maglite like torch quiting a
42
  Candela output in white, using THREE LEDs!! it was also 100,000 year
(Ten
  Years continuous use) LED life, and about 100 hours on three AA
cells..

  so I had a further rummage, and found what I believe to be the
highest rated
  white LEDS available on the market now...

  12 Candela units, from computronics in Australia. (they are selling
a bag of
  500 for about ?300 + shipping)

  The bizzare thing for me is this:

  the 2500mcd ones use 20mA at about 3.8V optimal..

  And the 12000mcd ones, despite being nearly five times brighter use,
er,
  20mA at about 3.8V

  I'm totally smitten!!

  The idea of having a cool crisp light (I like a slight blue tint at
the best
  of times, so the lack of any "red" component doesn't
bother me) that can be
  used with normal usage patterns for 25 years and uses about
>ONE< Watt in
  place of a 50W Halogen, whilst producing an equivelant 80W light
level is
  pretty amazing..

  I'm having ideas of totally cool under cupboard lighting, but having
twice
  as much light for about 4% of the leccy... :)

  more research required...

  as an aside, if we don't get a European supplier, is anyone
interested in
  chipping in for some of the LEDs from Computronics. I think it works
out at
  about 60p each. ?

  Ian



  -----Original Message-----
  From: paul_watkin [mailto:paul_watkin@xxxxxxx]
  Sent: 23 April 2002 20:31
  To: ukha_d@xxxxxxx
  Subject: White LED Lighting... was RE: [ukha_d] Re: ADSL vs
Cable


  Nichia have the brightest white LED's on the market at about 6.4cd
in
  a T1 3/4 package or 3.2cd in T1

  http://www.nichia.co.jp

  Not sure who in Europe holds a disty franchise for Nichia though,
try
  Arrow, EBV somebody like that. I'll try and find out who it is
  tomorrow.

  Other companies to look at are Panasonic, Lumiled (Agilent and
  Philips Joint venture to replace the lightbulb with led's) and
also
  Agilent Technologies.

  Although you would probably need an account with somebody like
Arrow
  or EBV to get access to stuff from the above suppliers.

  Regards

  Paul

  --- In ukha_d@y..., "PatrickLidstone"
<patrickl@t...> wrote:
  > >
  > > Due to really awful search functions (and every
electrical
  appliance
  > > containing LEDs), I can't find details.  There is a
3mm LED on
  the
  > Maplin
  > > site
  > > (http://maplin.co.uk/products/details.php?
  > cartid=0204231835361451415&modulec
  > > ode=&moduleno=17821&manufacturer=Nichia).  I
based my thoughts on
  > the
  > > variety of LED torches around.
  >
  > Rapid Electronics do a separate opto-electronics catalogue
-
  probably
  > worth a gander.
  >
  > You'll find full tech specs on RS (Radio Spares) and
Farnell
  websites
  > for a huge range of LEDs.
  >
  > Patrick



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