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Is this circuit possible? And what resistor should I use?

by JJM596
Tags: circuit, resistor
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JJM596
#1
Aug14-14, 03:05 PM
P: 3
Hi all,
I am a new member here.

I am quite new to making circuits,etc. and have decided to make something easy-ish on a breadboard. I have included a diagram of what I am planning to make. I am using 6x white
LEDs and a 9v battery. I was wondering what resistor I should use for
this? Also, is this even possible? Do I have enough power to light up 6 LEDs not full power
, as I know i dont have enough power for that, but even just a little bit bright? Would really appreciate
any help on this. apologies for bad grammar, am in a rush!

Thanks, Jamie
Ireland
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DennisN
#2
Aug14-14, 08:02 PM
DennisN's Avatar
P: 484
You could start with having a look at this: http://en.wikipedia.org/wiki/LED_circuit.
davenn
#3
Aug14-14, 08:36 PM
Sci Advisor
PF Gold
davenn's Avatar
P: 2,756
Hey there Jamie
welcome to PF

1k resistors ( as currently shown) would be OK as a starting point, then increase or decrease a little to get the brightness you want

Make sure you have the LED's the right way around


Dave

Baluncore
#4
Aug15-14, 04:26 AM
Sci Advisor
Thanks
P: 1,959
Is this circuit possible? And what resistor should I use?

White LEDs drop a forward voltage of about 3.3V.

Each LED will have (9V 3.3V) / 1kR = 5.7 mA. I would have expected Ifwd to be closer to a typical 20 mA.
For 20 mA you would use R = (9V 3.3V) / 20 mA = 285 ohms, use standard value 270R.
Total current will be 6 chains * 21.1 mA = 126.6 mA.

You can save energy by wiring LEDs in series pairs. Then for 20 mA LED current you need a series;
R = (9V 3.3V 3.3V) / 20mA = 120 ohms, a standard value.
Total current will be I = 3 chains * 20 mA = 60 mA.
So the battery should last twice as long.
JJM596
#5
Aug15-14, 08:44 AM
P: 3
Thank you for a quick reply:) This helps alot!
One more question though, can I use normal wire instead of using breadboard jumper cable wires?
I have "normal" wire so if I could use it it would save having to buy the jumper cables.

Thanks again,Jamie
Baluncore
#6
Aug15-14, 05:00 PM
Sci Advisor
Thanks
P: 1,959
yes.


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