Subtitles section Play video Print subtitles Hi, my name is Massimo Banzi and I am one of the co-founders of Arduino. Welcome to this series of videos about the Arduino Starter kit. In this particular video, we are going to start learning the basics of all the components that we are going to use in the rest of the videos. What we see here is is a set of electronic components and today we are going to build a very basic circuit. We are going to use a small LED connected to a button and when you press the button, the LED comes on. It's a very simple electronic circuit. It doesn't involve our Arduino board at all. And it is designed for you to understand all the basic elements that make an electronic circuit. So what is an LED? An LED is a small source of light. You can imagine it's like a light bulb, but it's more efficient, because it doesn't generate that much heat. Because it is an electronic component based on the semi-conductor. So LEDs are convenient for us, because they work at a small voltage. They can be powered by a small battery or the voltage that you can get from an Arduino board. So, what’s is a circuit? A circuit is a series of electronic components like this LED or this button using wires connected together Using wires electricity can flow through the components and each component is either able to transform the electricity into something else, like light like the LED does. Or for example the switch is a component that can open and close a circuit when you press on it. This particular button that I have in my hand keeps the circuit closed until I press the button, and it closes the circuit. Closing the circuit is a little bit like when you open a tap: you let the electricity flow through the button. You can imagine that Electricity is like water and the wires that we are using to make the connection are like pipes. The source of electricity is essentially the equivalent of something that pushes water into the pipes. So the first circuit that we are going to build is going to have the source of electricity pushing the current through the wires, a number of wires that connect to the button. Then the button will open and close the circuit and when the circuit is closed, the current will flow through the LED. and then we will use another component that I have here, called resistor. What happens is that the voltage of our battery is too high for the LED that we are using. Just to give you an idea, we are going to be using a source of electricity operating at 5 volts, which is the standard voltage at which the Arduino board operates. But this LED is only going to need about 1.7 volts. So how do we make sure the LED doesn't take too much current? Well, we are going to use a resistor. And this resistor is going to limit the amount of current that flows through the LED, keeping it at the optimum amount of voltage and current. How do we make the connection? Well, actually what happens with circuits is that you can take wires, and you can wrap them around, and you can create circuits like that. But that's not very practical. If you want to do a lot of experimentation, if you want to move components around, if you want to try different kinds of circuits, wrapping wires around is not exactly the best idea. So what are we going to do? We are going to use these components that you see here. This is called breadboard. The breadboard essentially provides a set of prearranged connections, and each one of the holes is actually connected underneath with a metallic spring. So when I plug a wire into the breadboard, the spring will hold on to the wire and it will connect to all the other holes in the same line of holes. Let's have a look. For example, this line of holes that I am pointing to, they are all connected together. So if I plug this wire in this hole, all the holes in the same column are going to be connected to this wire. If I take for example this resistor, and I plug the resistor in one hole in the same line, for example here. This is ok. So at the moment, the resistor and the wire are connected together. If I move this wire to the hole next to it, they are not connected anymore because only the wires in the same column are connected together. So, to explain this concept better, I have prepared here a circuit that contains all the basic elements that I told you about. This is the resistor, this is the push button, this is the LED, and this is a wire. So what's missing here is the source of power. What the circuit needs in order to operate is a source of electricity. In this case we are going to use the Arduino board as a source of electricity. The Arduino board can be powered through a battery or through a USB connection as you can see in this particular situation. We are not going to use the intelligence provided by the Arduino board. We are just going to use the power that comes from the Arduino board in order to learn how to build the circuit on the breadboard. We are going to connect this wire to the other leg of the resistor. You will notice that actually the holes on this side of the breadboard, they have a different pattern. Why is this? Because actually these two lines of holes follow a different connection pattern. The ones that cover the main area of the breadboard as I said, they are all connected along the column, while these lines are going all the way from one end to the other. These are two separate strips of holes, and each one of them is connected together. So, for example, if I plug this red wire at the beginning of this line of holes, I am actually connecting 5 volts to every single hole that you can see on this line here. This means that this resistor is now connected to this hole. Now I am going to take this black wire and I am going to plug it in one of these two holes. They are marked GND GND is the ground. It also represents the minus on your battery. If you look at a battery normally there's a plus and a minus. So, 5V represents the plus on this ideal battery, and the minus is here represented by GND. So, if i connected the black wire to the other line on the breadboard, now I have connected 5V to the first line of holes and the black wire to the second line of holes. Now if everything is done correctly, if I pressed the button, I would connect the resistor to the LED. This will complete the circuit and the LED will light up. wow. Ok, it's working. Ok, that was good. So the ability to convert the electricity into another physical phenomenon that we can actually experience in the real world makes the LED a transducer. The transducer is a component, which is able to convert electricity into something else. or for example if there were a component that would convert the light back into electricity that would also be a transducer. In particular we call the LED in this particular situation an actuator because it takes electricity and then turns into something that I can actually see in the real world. In this case, I can see light. Electricity is invisible to me, but the LED makes the electricity visible by turning it into light. We have our completed circuit and I would like to make some modifications now to introduce some other concepts. So what we are looking at here is a very simple circuit, where each component is connected to the next component in the circuit, and then the last connection goes back to GND. You can imagine the current flowing from the red wire, into the circuit through the resistor, through the push button, then in this wire, then through this LED, another wire back to ground So, this is how the circuit is closed. One of the features of the circuit is that the elements we say that are connected in series. Because one component comes after the other. And we can make the circuit a little bit more complicated, because at this moment we have only one button. So what happens if I connect to another button? I can remove this jumper, and then I am going to add another push button, making sure it's connected with the LED. So now, when I press these buttons nothing happens, because the circuit is still open. We have to close the circuit using one of these wires. So, I will plug the wire here I will plug the other wire here. And if everything works out, I press the button, and still nothing happens, why? Because these two buttons are connected in series, so they are one after the other. If I want to operate the circuit, I need press both buttons at the same time. So look at this, when I press button number one and button number two the current is able to flow through the circuit. and when I release one of the buttons, the circuit is open and it stops operating So what we have learned now is that if we put buttons in series, one after the other, I need to press all of them in order to close the circuit and make the electricity flow. Inside the push button there are two pieces of metal. They are separated by a spring. When you press the button, these two pieces of metal, they come in contact. and they create an electrical connection, and the electricity can flow through them. When you release the button, the spring pushes the two pieces of metal away and it interrupts the circuit. It opens the circuit. So you will notice that the push button has got four legs. At the moment we used only two. What are the other two legs doing? Well, actually they are internally connected to the first set of the legs. So the two legs on this side of the push button are internally connected together and the two legs on this side of the push button are internally connected together. This increases the number of combinations that you can use when you create circuits. So, what happens if I take this jumper that I used to build this circuit. I can actually mount it behind the push buttons. And the circuit still works. What you will notice is that this point of the circuit and this point of the circuit are exactly the same. And here this point and this point are exactly the same. So, when I press the button these two points in the circuit are connected with these two points in the circuit. When I release the button, only these two points are connected and these two points are connected individually, but there's no connection between the four of them. This allows me to try to create another connection that we call parallel connection. The idea is that we can actually place one button next to the other and we can create two different paths that the current can use to actually flow through. Let's see what happens if we put these two push buttons in parallel? So what I am gonna do, I am going to use two jumpers. I am going to connect one leg of the first push button with the same leg on the second push button and I am going to do the same for the remaining contacts, one and two. What happens here is that if I press the button now the LED comes on. And if I press the other button, the other LED comes on. And if I press both of them, the LEDs come on at the same time. So, what's happening here is that by creating two different paths for the current to flow through, I just need to press one of the two buttons for the current to reach the LED and light up. If you put the buttons in series, you need to press one button and the other button in order to create light. And in this particular configuration, you need to press one button or the other button in order to turn on the LED. So in a way, this small circuit is creating a very basic logic circuit. One that has an "and" logic, you need to press one button and the other in order to light up the LED. And the second one is an "or" circuit, you press one button or the other. That's all for today. I hope you enjoyed the tutorial. And remember: build it, hack it, share it, because Arduino is you!
B1 circuit button connected led electricity arduino Arduino Video Tutorial 01: Get to know your Tools with Arduino CEO Massimo Banzi 123 7 Chuan Zhe Lin posted on 2013/05/20 More Share Save Report Video vocabulary