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Electronics => Electronics => Topic started by: blake on September 01, 2009, 04:36:35 AM

Title: resistors and LED's
Post by: blake 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 ?

Title: Re: resistors and LED's
Post by: SmAsH 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 (http://led.linear1.org/led.wiz)

Title: Re: resistors and LED's
Post by: Soeren on September 02, 2009, 07:13:07 PM

Hi,

Quote from: blake on September 01, 2009, 04:36:35 AM

[...] a 1.2 volt LED [...]

What kind of LED would that be?

Title: Re: resistors and LED's
Post by: GearMotion 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 (http://www.theledlight.com/LED101.html)

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

Title: Re: resistors and LED's
Post by: Admin on September 05, 2009, 06:24:41 AM

http://www.societyofrobots.com/electronics_led_tutorial.shtml (http://www.societyofrobots.com/electronics_led_tutorial.shtml)