Must be connected backwards. LEDs are polarity specific: LED Info

Thanks for the quick reply DJ

Tried LED both ways (polarity), but still not turning on. Maybe I have 2 faulty LEDs...?

They were working before pulling apart the WALL-E though.

Connect one side to GND and the other to a SIGNAL pin of the EZ-B?

Yes, that's what I did.

Did you use the original LED for the eye on WALL-E?

I can't remember. I probably would have. I usually do use the LED's that come with the toys

Hey Hexxen,

Sometimes LEDs cannot self limit the current going through them and burn out when direct voltage is applied. Usually a 330 ohm or 220ohm resistor is needed to limit the current going through the LED to around 20mA for common 5mm LEDs.

EZ-B puts out 5V (TRUE) on each I/O pin, so using ohm's law Voltage = I(current) * Resistance 5V = 20mA * R

R = 5V/20mA = 250 ohms so the closest more common resistor values are 220 and 330 ohms. 330ohms is the safer value cause it limits the current going through the LED to 15mA. This resistor can be in series with the LED on either the anode (+) or cathode (-) of the LED.

Hope the mini-tutorial is useful

I never use a resistor with the EZ-B because digital I/O on the EZ-B has a source supply of 25mA only. All of my robots are just LED's connected directly to Signal and GND.

*Note: If you were to use Signal and +5, then you will need a resistor. And your LED would always be on.

Thanks for your help guys.

It turned out to be both original LEDs were faulty (I must have blown them somehow).

Tested a LED I pulled from a LED torch & it works fine with the EZ-B.

Now that I need to get some new blue LEDs for WALL-E, was thinking of using "color changing LEDs" instead to simulate Wall-e's different moods.

Will the color changing LEDs work with the EZ-B?