LED Resistor

[SirBob]

Hi,

This is probally a very easy question for the people that are concerned with electronics but...

I have a pushbutton with a 2.2v 25mA LED indicator in it. What size drop down resistor do I need to put in seris with it to run it at 24vdc.

Many Thanks

Bob

 

[flat5]

r=e/i
r=24-2.2/.025
r=872
or slightly more resistance to use a standard value.
1k is a good choice

p=E (of the resistor) x I
(or I x I x R)
p=21.8 x .025
p=.545 watts
a 1 watt resistor should be used

 

[dog812]

This may also help in the future..
Current limiting Resistor calculator for leds

 

[SirBob]

Many thanks to you both.