Logic Gates - An Introduction To Digital Electronics - PyroEDU

In the previous lesson we took a look at two number systems binary and decimal that are actively used in

digital

electronics

. In this lesson we will go ahead and apply the on and off true/false quality that the binary number system offers us and we will see. How it applies to

logic

gates

and Boolean algebra Boolean algebra uses three operators to perform mathematical Boolean operations, whether or not they are

logic

gates

, they are a graphical way of representing Boolean algebra equations through logic diagrams and with a drawn logic diagram, can go into

digital

hardware and actually builds the circuit, the first boolean expression and logic gate that we'll look at is called a gate and graphically it looks like this symbol and algebraically it's represented by this dot, but just like in multiplication, you can actually Having two input symbols x and y together means that they must be ANDed.

The way this logic gate works is with binary inputs, the inputs and outputs are defined by what is called a truth table, as you can see on your screen. Now this truth table shows that only when both inputs are logic, a logic gate output of logic 1 can be achieved if either of the inputs is a logic 0, the output of the gates and is also a logic 0, the following boolean operator and logic gate that we will see is called the o gate graphically it looks like this, a more curved version of the gate and the boolean algebra representation of o is a plus sign just like with the gate and in o the logic gate has a truth table defining its function here, truth table shows us that when any of the input signals is a logic 1, the output is a logic 1, only when both inputs are logic 0, the output becomes logic 0 , the next boolean operator and logic gate is called the not gate and in boolean algebra it is represented by putting a line over the input like this, the not gate is the simplest of all logic gates because all it does is invert the signal. input from logic 1 to logic 0 or logic 0 to logic 1, so the truth table looks like this: The final boolean expression and logic gate we will look at is called an XOR gate and its boolean algebra symbol looks like this: The logic, however, if any of the inputs are 1, the output is a logic 1, this may seem like a strange operation, but the more tools we have in our digital logic toolbox to solve problems, the better these gates will be. logic the basis of digital

electronics

.

If you delve into the theory of logic gates, you can discover that there are other types of logic gates, but they are all a combination of and/. logic gates or not that we just met as we would expect by building a circuit and checking the truth table first, let's check and gate the 74 HC zero eight. I see it is a quad and gate device. This circle can be found on any integrated circuit chip you point to. you know that pin 1 is right next to it, from that point you can count the id of each pin as you see on your screen for the logic that ICS will use.

Pin 7 is always ground and pin 14 is always plus 5 volts VCC the 74. HC 0 8 IC has four gates and inside with each of the inputs and outputs connecting two different pins on the IC you will only need one gate and for this experiment, so we will only use pins 1, 2 and 3. Here is the schematic of the circuit, we will build this circuit to test the final gate and if you look closely you can see that the inputs to that and the gate are the pins 1 and 2 and the output is pin 3. The parts used in this experiment are jumper wires from the cable kit and a board from the component kit, we will need a 9 volt battery connector, a +5 volt regulator 7805 , 3 red LEDs, a 9 volt battery, a 74 HC 0 8 IC and 3 100 ohm resistors, so let's set up our experiment, we are going to want to run everything on a +5 volt supply, so we will use a 7805 voltage regulator on the top of the breadboard here 10 1 connects to the plus 9 volt connectors, the red wire input 2 connects to the plus 9 volt ground, the black wire and pin 3 is the +5 volt output of the 7805 will connect pin 3 of the 7805 to the power bus line with a yellow wire and pin 2 to the ground bus line with a green wire to the red wires. connect the +5 volt power and ground to a second bus line on the breadboard, the 74 HC 0 8 and the gate IC will be placed in the middle.

Please note that it fits perfectly. The proofing plates are designed to be used specifically with this type of built-in pea sauce. The circuits connect a +5 volt supply to pin 14 and ground to pin 7 and now we are ready to test the gate and to confirm the truth table. We will need to give the door and two entrance signs and see the exit according to the diagram. We will connect three 100 ohm resistors to the gate and on pins one, two and three and then we will connect each of those resistors to an LED that goes to ground. These three LEDs will represent the two inputs to the door and and the output of the door. and door if an input or output to or from the door and it is logical the LED will turn on if it is a logical 0 the LED will be off with the battery plugged in the system is on the two yellow wires will be used to change the state of the system, the The first state we are looking at now is the input of 0, which produces an output of 0.

Now, using the two yellow wires, we will switch the input states between logic 0 and logic 1 to verify the truth table. when the input is 0 1 the output is 0 when the input is 1 0 the output is 0 and when the input is 1 1 the output is 1 and this is how the logic gate works and let's perform the same experiment with the o gate as the previous I see this 74 HC 32 IC has 4 inputs or dual gates inside it. Here is the schematic we will build. The only difference is that we are using a 74 HC 32 or gate IC, which means you can actually remove the IC from the old one.

Experiment and place the 74 HC 32 in exactly the same place. Now let's go over the truth table again and verify that the o gate does what we theoretically expect when the input is 0 0 represented by the LEDs on the left side the output is 0 when you change the input to 0 1 the output is logic 1 by changing the input to 1 0 the output is still logic 1 and finally we test when the input is 1 1 and you can see that the output is also a logic 1 represented by the LED on therefore the o gate exactly follows the theory, the last device The one we will experiment with is the gate not for hc0, since within this I see that there are 6 knot modules that we can use if you remember from the theory section, the gate is not an inverter. whatever is input, the opposite is the output.

Here is the schematic for this experiment. Note that this time there are only two LEDs because there is only one input and one output one gate not for this circuit you will place the IC in the middle of the board and add power and ground connections then the 100 ohm resistors they connect to pins 1 and 2, followed by 2 LEDs connecting from those resistors to ground, finally a yellow wire is added to give input to pin 1, now you can see the input on the left. -right side and the output on the right side when the logic 0 is connected to the input of the 74 HC 0 4 on pin 1, the output on pin 2 is a logic 1 and if we change the input to a logic 1 the output changes to a logic 0 since this 74 HC 0 4 is an inverter it is working perfectly and we have just verified its truth table the component kit also includes an xor gate at 74 86 a NAND gate at 7400 and a Donora gate at 7400 for take some extra time and find the truth tables for these devices and check and verify that they follow the truth table using the method we just experimented with, while logic gates alone are difficult to find in the real world, its true place is in the big picture.

They are called logic diagrams. A logic diagram like these produces a single output given multiple inputs, just like cars at a four-way intersection with a traffic light. The sensor in each traffic light must know whether a car is present or not to determine whether to turn. a green light beyond graphical logic there is a written style of logic called boolean algebra that represents the complex input and output system of digital logic and allows you to more easily play with numbers to simplify them we will learn more about boolean algebra in the next lesson, on a final note from the real world, digital logic, the idea that things have two states, either on or off, true or false, is also widely used in programming languages ​​across the board, you can see the true and false of ORS in simple English or represented by simple symbols, but in reality they are performing the same simple task that a digital logic or a gate or a gate do all the parts in this online course provided to us by the Ori gadget , visit them at gadget or EECOM slash pyro edu next time We will start studying more about boolean algebra and carnivals.

In this way we will see how logic gates can be combined to solve and simplify complex Boolean equations.