Bread Board Power Input?


I am new to the Arduino Community; this is my first post. I hope to learn the basics of circuits through a starter guide that came with with an arduino a family member gave me as a gift.

The starter guide came with a few programmed circuits, and an instruction book I am using to learn the basic vocabulary, and assemble the physical components. Attached is the first circuit’s sketch. I was able to assemble and build the circuit, but I have a couple questions regarding the design and necessity of components in the circuit.

In the assembly documentation, the starter guide recommends three wires: 1)5V analog output to + terminal on bread board, 2) Analog ground to negative terminal on bread board, 3) wire from pin 13 to the same row as the + terminal of the led.

I setup the circuit, uploaded the sketch, and successfully got the LED to blink. However, while I was disassembling the circuit, I noticed that removing the 5V to positive terminal wire had no effect on the blinking of the LED. Is the 5V wire necessary? Why is the 5V wire included in the documentation if it’s not necessary?

Thank you,

Circuit_01.ino (4.82 KB)

Never change the wiring while power is applied to it. That is a sure fire way of destroying components.

Now you know what kit you have but we don't. We don't know how you wired it up. You do not mention the resistor that you need with the LED either so your description leaves a lot to be desired, or the tutorial is crap because it doesn't use a resistor.

Why is the 5V wire included in the tutorial? A crap tutorial.

I think it’s user error.
Not sure what OP means with “the 5V to positive terminal wire”.
Maybe we have to see a picture.

Here is the sketch with most of the comments removed.

Hardware connections:

  Most Arduinos already have an LED and resistor connected to
  pin 13, so you may not need any additional circuitry.

  But if you'd like to connect a second LED to pin 13, or use
  a different pin, follow these steps:

    Connect the positive side of your LED (longer leg) to Arduino
    digital pin 13 (or another digital pin, don't forget to change
    the code to match).
    Connect the negative side of your LED (shorter leg) to a 
    330 Ohm resistor (orange-orange-brown). Connect the other side
    of the resistor to ground.

    pin 13 _____ + LED - _____ 330 Ohm _____ GND
    (We always use resistors between the Arduino and and LEDs
    to keep the LEDs from burning out due to too much current.)

This sketch was written by SparkFun Electronics,

void setup() {
  pinMode(13, OUTPUT);

void loop() {
  digitalWrite(13, HIGH);   // Turn on the LED
  delay(25);              // Wait for one second
  digitalWrite(13, LOW);    // Turn off the LED
  delay(25);              // Wait for one second

I wired the board according to this graphic.

The LED is powered from Digital Pin 13.

digitalWrite(13, HIGH) will give 5v to pin 13 thus LED get power.
digitalWrite(13, LOW) will give 0v to pin 13 thus power off the LED.

5V from Arduino is connected to power rail of bread board but the led is not connected to it. That means blinking of led is not dependent on Arduino 5v pin. For this blinky experiment, the 5v from Arduino is not required.

LED wont blink if you remove GND connection from Breadboard.

Attached OP’s instruction manual from the post


If you still have the USB connected from your PC to Arduino, the Arduino will get +5 V from there. In this case you are providing +5 V from the Arduino to the solderless breadboard power rail. It's not used in this example, but probably is in other examples.

If you don't have the USB connected and you have power to the breadboard then it's possible that the Arduino is getting back powered through the LED and resistor as the previous poster suggested.

The way that circuit is wired, the +5 rail of the breadboard is not connected to anything, so the wire going to it can be removed without making any difference.

The wiring showing it connected is probably boiler plate - the +5 rail will be used in other projects.

And yeah, you probably shouldnt be connecting and disconnecting wires while it's running if you don't know what you're doing. It's oh-so-convenient, but there are cases where connecting things in the wrong order can cause a problem, and without more experience, you won't know when that is. (The case that comes to mind is connecting power to an IO pin of something, when that something isn't powered itself - most devices really don't like that)

Thanks everyone for walking me through this Circuit, and the pointers for proper breadboard technique!