# Wiring LED's

Discussion in 'General Electronics Chat' started by Paulquinn, Aug 29, 2013.

1. ### Paulquinn Thread Starter New Member

Aug 28, 2013
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Hey guys quick question. Is it better to wire LED's in parralel or
In series?

2. ### #12 Expert

Nov 30, 2010
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If you put as many LEDs in series as the voltage supply will allow, you will use the least number of resistors, compared to installing a resistor for each LED.

3. ### Metalmann Active Member

Dec 8, 2012
700
223

Most say in series, lately I've been using parallel with no noticeable side effects......

4. ### mcgyvr AAC Fanatic!

Oct 15, 2009
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Out of curiosity.. Do you have a "current limiting device" (or current mirror) for each series string in that parallel circuit or just hoping they will share the current equally?

Have you read up on "LED thermal runaway" ?

5. ### wayneh Expert

Sep 9, 2010
12,386
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You need to define your meaning of "better".

As #12 has noted, a series arrangement allows you to limit current through several LEDs with a single resistor (depending on your power source and LED voltage drops). So it is "better" because it uses less parts and wastes less energy.

But if you need to light 20 LEDs and you only have a 5V supply, it cannot be done without a parallel arrangement. So then parallel is "better", since it's the only choice.

I think the fast and simple strategy in most cases is to use as many in series as you can and then put more strings in parallel when you need to.

One thing that does NOT work well is LEDs in parallel without individual current limiting. You can put current-limited STRINGS in parallel, but not un-limited LEDs themselves.

6. ### Paulquinn Thread Starter New Member

Aug 28, 2013
5
0
Ok should have worded it better.
I mean most efficient. If I have several LEDs
Not enough so I would loose voltage by running in series
Is it more efficient for the led to run parallel because each one has
It's own resister? Alot of diagrams I've seen have shown a few LEDs
In parallel.

7. ### #12 Expert

Nov 30, 2010
16,690
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No. You got the right answers, even if it does seem a matter of luck.

8. ### wayneh Expert

Sep 9, 2010
12,386
3,244
Just the opposite. Every path from "+" to "-" that includes an LED will have the same current, for example 20mA. This current is defined by the LED's specification. The power consumed in that path is the voltage of the supply times that current, for example 12V x 20mA = 240mW.

This does not change if you add more LEDs in series. So adding as many LEDs in series as you can, and reducing the value of the current limiting resistor, gives more light without requiring any more power. It's therefore more efficient. Power that was dissipated by the resistor is instead used to make more light.

Each string added in parallel to the first will consume another 240mW. If the strings are identical, the efficiency is unchanged.

9. ### Metalmann Active Member

Dec 8, 2012
700
223
"Have you read up on "LED thermal runaway" ?"

Certainly.

10. ### mcgyvr AAC Fanatic!

Oct 15, 2009
4,791
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and does each series string have current limiting?
or do you hope they will keep sharing current..
and how much variation have you seen in currents..
I'm just interested...

Mar 24, 2008
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