Super simple LED flashing... only works with NO resister

HI -first 30min with this thing... feel very stupid asking such a simple question.

Wrote a simple program to flash an LED using pin 13, this all worked on the board, the little light flashes but not when using a real LED

Wired up the LED on a bread board with a resister as shown on utube but the LED would not work, so after mucking around I found it works without the resister.

Pin 13 - LED+ to LED- to neg = flashing LED.

Why does it work?
Using PC - USB to power the board... is the voltage to low?

At least I got the LED to flash but not wired how it should be.
thanks

There is a mistake in the wiring of one of the early Arduino boards.

Which one are you using and specifically, is it a genuine Arduino or a clone, please cite the actual Web page describing it?

so after mucking around I found it works without the resister.

Pin 13 - LED+ to LED- to neg = flashing LED.

Why does it work?

The question is why will it not work with the resistor?

  1. because the resistor value you are trying to use is too high, are you reading the colours from the right end?
  2. because you have not got it wired like you think, either the layout is wrong or the connections are not being made on the breadboard.

It works without the resistor for now, but without a resistor you are damaging both the led and the Arduino pin.