led question

K

Klemen

Guest
Hi!

I'd like to connect 5 leds, but i'm not sure which way is better. Is it ok
to connect them in series with a restitor to limit the current, or should i
connect them parallel each with the resistor?

regards
Klemen
 
Klemen wrote:
Hi!

I'd like to connect 5 leds, but i'm not sure which way is better. Is it ok
to connect them in series with a restitor to limit the current, or should i
connect them parallel each with the resistor?

regards
Klemen
Either of those may work, but connecting several in series may make
more efficient use of the supply voltage, if it is quite a bit higher
than the LED requirements. What supply voltage are you using, and
what color of LED?

--
John Popelish
 
I'm using 12V(actually 14V because it's a car battery) power suply and
bright blue leds.

thanks for your replies


"Klemen" <nec4b@email.si> wrote in message
news:bdsqpj$gvg$1@planja.arnes.si...
Hi!

I'd like to connect 5 leds, but i'm not sure which way is better. Is it ok
to connect them in series with a restitor to limit the current, or should
i
connect them parallel each with the resistor?

regards
Klemen
 
Klemen wrote:
I'm using 12V(actually 14V because it's a car battery) power suply and
bright blue leds.
Since getting the utmost efficiency is not so important (unless you
are going to leave them on for days without running the car) I would
connect them in series in pairs , with a resistor for each pair.
Since car battery voltage can spike around and vary quite a bit, I
would go for about 10 ma (.01 amp) average. Blue LEDs drop about 3.5
volts, each, so a pair will use up about 7 volts. That leaves about 7
volts to be dropped by each resistor while carrying about .01 amp.
7/.01=700 ohms, which is not a standard 5% value. 680 or 750 ohms
would work fine. The heat produced in each resistor is about
..01*.01*700=.07 watts, so 1/4 watt resistors are plenty big.

--
John Popelish
 
Hi!

The way you connect 5 leds doesn't make a difference in terms of theory.
You can build parrarel or series cicuit. Either way is good because in both
connections current flowing through leds must be the same and the voltages
dropped on them also. So, the only difference betwen both types of
connection
is the voltage applied and the number of resistors. You should decide which
is better: use more resistors and less voltage or vice versa.

Tradius:)
 
Thank you everyone for your help!

regards
Klemen


"Klemen" <nec4b@email.si> wrote in message
news:bdt167$m8g$1@planja.arnes.si...
I'm using 12V(actually 14V because it's a car battery) power suply and
bright blue leds.

thanks for your replies


"Klemen" <nec4b@email.si> wrote in message
news:bdsqpj$gvg$1@planja.arnes.si...
Hi!

I'd like to connect 5 leds, but i'm not sure which way is better. Is it
ok
to connect them in series with a restitor to limit the current, or
should
i
connect them parallel each with the resistor?

regards
Klemen
 
John Popelish <jpopelish@rica.net> wrote in
news:3F01F202.DC96F1E0@rica.net:

Klemen wrote:

Hi!

I'd like to connect 5 leds, but i'm not sure which way is better. Is
it ok to connect them in series with a restitor to limit the
current,
or should i connect them parallel each with the resistor?

regards
Klemen

Either of those may work, but connecting several in series may make
more efficient use of the supply voltage, if it is quite a bit higher
than the LED requirements. What supply voltage are you using, and
what color of LED?
So when one goes bad they all go out .
roma
 
roma wrote:
John Popelish <jpopelish@rica.net> wrote in
news:3F01F202.DC96F1E0@rica.net:

Klemen wrote:

Hi!

I'd like to connect 5 leds, but i'm not sure which way is better. Is
it ok to connect them in series with a restitor to limit the
current,
or should i connect them parallel each with the resistor?

regards
Klemen

Either of those may work, but connecting several in series may make
more efficient use of the supply voltage, if it is quite a bit higher
than the LED requirements. What supply voltage are you using, and
what color of LED?


So when one goes bad they all go out .
roma
If it goes bad by going open circuit, then that string will go out.
If it goes bad by going short circuit, the rest of the string gets
brighter. If the LEDs are operated well within their ratings (say
half of maximum current rating) either case is very unlikely in your
lifetime.

--
John Popelish
 

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