# How to wire up this LED?

Hello there,

I've bought this cluster of red LED's from Maplins and I'm unsure how I should go about making a circuit that lights them up using a 9 volt battery. (I also have a simple switch).

The forward voltage of the LED is 2.5v and the forward current is 30mA. According to my calculations I would need to put a 1/2W or greater 220 ohm resistor in the circuit. Is this correct?Also how do I go about wiring the cluster up as they are in fact 6 individual led's. Do I need a resistor for each?

My knowledge of electric circuits is limited.

Many thanks,

Julian

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iceng4 years ago
Wire it three LEDs in series with a 50 ohm resistor as two sets going

3 × 2.5 = 7.5 volts
A resistor needs to drop 1.5 V  / .030 A  ==>  50 ohms.

A
Joachimanderson (author)  iceng4 years ago
Brilliant! Many thanks for your advice. Going to try this this evening.

Many thanks,

Julian
4 years ago
Great, if it works 4 U.
I hope you mark the best answer :)
frollard4 years ago
I can't make out exactly what that circuit diagram you attached says. It looks like some of the leds are in series and others are in parallel - not knowing how they are hooked up internally we can't suggest what you need. If they are all individual LEDs with their own legs its very easy:

1) Do not use 9v batteries. They are expensive and their total energy storage is crap. Get a AA or AAA battery holder - it will pay for itself after one or two replacements. Preferably use rechargable AA's.
4xAA = 6V
6xAA = 9V
2) Use a series/parallel resistor calculator to figure out what circuit to make. http://led.linear1.org/led.wiz
9volts, 6 leds, 30mA, 2.5V each
leaves 2 strands of 3 leds in series with a 56 ohm resistor on each strand (also in series). The 2 strands are then connected to the power source in parallel.
Joachimanderson (author)  frollard4 years ago
Thanks for your help and advice. Got myself an AA battery holder and try out your circuit. I think the Led's are all individually mounted within the light.

Many thanks,

Julian