LED's - Resistors Needed?

C

chrisdicko

New Member

• Feb 22, 2010

• #1

I am fitting some LEDs to give an indication if interlocks are located properly on a machine, and have ordered these LEDs: RS | Relays, Switches and Indicators | Indicators | Lamp, Panel Mount | LED Indicators, 6mm Mount, 12 & 24Vdc

I am using 6 of them. Do I need to run a resistor with each one in series? If so, which size?




Thanks a lot

 

audioguru

Well-Known Member

Most Helpful Member

• Feb 22, 2010

• #2

The very dim LED already has a resistor inside to limit the current when it is powered from 24V.
I haven't seen an LED as dim for about 45 years.

They are extremely expensive for such a dim old LED.

 

C

chrisdicko

New Member

• Feb 22, 2010

• #3

Oh right, they aren't too good then? I just searched on RS and they fit my criteria. They don't have to be bright to be honest, just bright enough to show if they are on or not really.

Can I ask, how do you know there is a resistor built in?


Thanks a lot

 

audioguru

Well-Known Member

Most Helpful Member

• Feb 22, 2010

• #4

chrisdicko said:

Can I ask, how do you know there is a resistor built in?
Because an old green LED is about 2.2V. It needs a resistor in series so it can be powered from 24V.

Click to expand...

 

Hero999

Banned

• Feb 22, 2010

• #5

The LEDs might be dim but they are diffused so they will have a very wide viewing angle.