6v Led

Using Arduino LEDs and Multiplexing
#1

(newbie question)

I have some 6v LEDs (built into some push buttons)

From what I know (and its not much) resistors are used to drop the volt for leds to protect them, but I read a lot about protecting the arduino outputs too. Do I need to use a resistor in some what when I connect a 6v led directly to a output pin?

They work fine now..

Thx Gary

#2

You must measure how many milliAmps the LED uses. insert a multimeter in between, Arduino can deliver 50 mA per pin max (IIRC) but between 1..10 is better.

#3

Arduino can deliver 50 mA per pin max (IIRC) but

BZZZZT! 40mA ABSOLUTE MAXIMUM Don't go anywhere near this value

#4

garyd: (newbie question)

I have some 6v LEDs (built into some push buttons)

From what I know (and its not much) resistors are used to drop the volt for leds to protect them, but I read a lot about protecting the arduino outputs too. Do I need to use a resistor in some what when I connect a 6v led directly to a output pin?

They work fine now..

Thx Gary

Do you have a link for the pushbutton/led device? If it's led is truly designed to wire directly to 6vdc then that implies that is already has internal current limiting resistor. If that is the case then it should be no problem being wired directly to an arduino output pin and ground. However that is an assumption that should be be verified by reading the datasheet for the device.

Lefty

#5

Its this one http://www.onpow.com/en/product/product1169.html cant seem to find any values for the 6v version..

#6

garyd:
Its this one http://www.onpow.com/en/product/product1169.html cant seem to find any values for the 6v version…

Not the best documented device, but I did find another link for it that gives this little hint:

Note: There are protective resistor in the lamp, special voltage rate can be made to order.

http://www.hy1688.com.tw/SWITCH/PUSH%20SWITCH/PDF/LAS2-GQ.pdf

I would say that’s safe to wire the 6vdc led terminals directly from an arduino output pin and ground as the internal “protective resistor” will prevent damage to the output pin and the internal led. However what don’t see is a wiring diagram to tell you the correct pin numbers and polarity for the led section of the device, so you will have to experiment with it I guess.

Lefty

#7

Polarity and NC NO pins are written directly on the button, so no problems there, and they work just fine... I simply shorted my board this morning (with some screw mounts) and was first worried that it was the leds, so thought I better check up..

#8