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Just re-read what Frank was saying here and I
think I
missed the point - in a long run of LEDS then you will need to run a pair
of
wires for the each 3 LEDS in my scenario - (actually not strictly
true but
one extra wire connecting the three together) - it's still a better
solution but
I agree it is a touch more complex to wire.
Kevin
The wiring complexity is really the same in both
situations - you need just two wires to each led - in the series solution
you
save four connections as you lose two resistors and also you only have to
break one of the wires at each LED so you save 3/6 connections
there. You just interrupt one strand of the cable at each led (except the
last
one) v having to connect across each time. If anyone wants I'll draw a
diagram.
Kevin
Quite Correct Keith
But from a wiring point of view were there are a string
of leds along a skirting in a hallway for instance i would imagine
wiring them individually using speaker wire in parallel would be easier
especially for guys who are not into electronics.The 3 in series is
good for a cluster were you need more lite .
Frank Mc
----- Original Message -----
Sent: Wednesday, April 24, 2002 10:19
PM
Subject: RE: White LED Lighting...
was RE: [ukha_d] Re: ADSL vs Cable
If you put 3 LEDs in series you only need one resistor per 3
LEDs
Power disipated (WASTED) by the resistor is also reduced to a third
as it is only dropping 3v now.
also using the series method you are lighting 3 LEDs with only 20mA
compared to 60mA if driven individually.
Total power consumption is now 33% of what it would have been.
Smaller transformer + thinner wire + less power = lower
running costs = more money left for toys :-)
Keith
www.diyha.co.uk
www.kat5.tv
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 -----
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@xxxxxxxSubject: 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@xxxxxxxSubject: 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@xxxxxxxSubject: 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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