### Author Topic: resistors and LED's  (Read 1088 times)

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#### blake

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##### resistors and LED's
« on: September 01, 2009, 04:36:35 AM »
hi, Blake here , i was wondering if someone could tell me what resistor to use if i was running a 1.2 volt LED from a 9v battery ?

#### SmAsH

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##### Re: resistors and LED's
« Reply #1 on: September 01, 2009, 04:39:53 AM »
this should be in the electronics forum
the formula for determining a resistor is (supply voltage)-(voltage drop)/(current in amps)
so it would be 9-1.2/.02=390 so a 390 ohm resistor will do
if you're lazy you can also use this site http://led.linear1.org/led.wiz
Howdy

#### Soeren

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##### Re: resistors and LED's
« Reply #2 on: September 02, 2009, 07:13:07 PM »
Hi,

[...] a 1.2 volt LED [...]
What kind of LED would that be?
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

#### GearMotion

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##### Re: resistors and LED's
« Reply #3 on: September 03, 2009, 09:54:02 AM »
Here is something helpful on LEDs. It is an "LED 101" from The LED Light: http://www.theledlight.com/LED101.html

Hope that helps you learn a little about LEDs and supplying them with voltage and current.

#### Admin

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##### Re: resistors and LED's
« Reply #4 on: September 05, 2009, 06:24:41 AM »

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