Hello everyone, welcome to the ZimZimDIY channel. Today, I will explain about diodes. What are their functions and how do they work? Let's look at most of the diodes that we often see on electronic circuit boards. They will look like this. They have a black cylindrical body. They are the main pattern like this. And they will have different sizes and shapes depending on the voltage and current that they can withstand. But what they have in common is that one end of the strip will be white. Remember that it is the negative terminal or K. Therefore, of course, the other side will be the positive terminal or A. The symbol in the circuit will look like this. It will be a triangular arrowhead with a line. If it points in which direction, the current will flow in that direction. If you compare it to the structure, it will look like this. Now, if we bias the diode forward, or Forward bias, it is to feed the positive terminal of the power supply into the positive terminal of the diode with a voltage higher than 0.7V. The current will start to flow from the positive terminal of the power supply into the A terminal of the diode, out the K terminal to the load device, and then flow into the negative terminal. And this is 1. In its function It will force the current to flow in one direction. And when the current passes through the diode, it cannot flow back. This property is similar to a one-way valve used in a water supply system. When water flows through the pipe, it will push the valve to the top. But when the water changes direction, it will hold it back, preventing the water from flowing back. Diodes do the same in electricity. To help you see the advantages of diodes clearly, I will give an example of a diode that is actually used in a solar cell circuit. Non-na type. The principle of its operation is that when the sun is bright, the solar panel will create a certain amount of voltage and current to charge the battery during the day, right? But when the sun is weak or at night, the voltage on the solar panel side will start to drop. If the charger does not have a diode to block the power from the battery, the battery that has stored current all day will flow back to the solar panel. It may damage the solar panel. Or burn it at all We can prevent the current from flowing back by using only a single diode connected in this way. Now we can solve this problem. When the sun is bright, it works normally. When it is dusk, the current does not flow back to the solar panel. The inverter can draw electricity to use at full capacity all night. Most common diodes that we see are mainly used to rectify AC signals. That is, if we have a sine wave like this, or a full wave, a pure sine wave, and connect it to 1 diode, we will get a half wave like this to use. Or what is called a half wave because the - voltage will be cut off, leaving only the + voltage. And it does not have to be a sine wave. Square waves can be rectified. Triangle waves can also be rectified. When the waveforms are superimposed, the peak voltage that passes through the diode will disappear when compared to the original wave. This is because the diode has a voltage drop of about 0.7 V. But it is not exactly 0.7 V. It depends on the temperature, current, and type of diode. Let's look at this picture. This will simulate the operation of the id. If I have 0.2 V power, the result is nothing because the voltage is not enough to bias 0.7 V. Now, let's do it again. I will change the power supply to -5 V. What do you think? Of course, the diode will not conduct current. And it is even worse than before because the voltage is negative. And the last example, I will give the power supply as 3 V. It turns out that the current flows. Because the bias is polarized and there is a minimum voltage that is sufficient, it causes the current to flow. If you try to measure the voltage drop, you will measure 0.7 V. When the power supply is subtracted from the voltage drop, there will be 2.5 V left. Therefore, if we use a multimeter to measure the voltage from here, it must also be 2.5 V. If the 10 V power is subtracted from the 0.7 V voltage drop, the remaining voltage will be 9.3 V. If the 20 V power is used, the remaining voltage will be 19.3 V. Of course, diodes have their own voltage resistance specifications. And diodes also have limitations in current resistance. The diodes that we commonly use Most electronic circuit boards are about 1A diodes. The energy lost by the diodes is determined by the formula Vf x the current flowing through the diode. Therefore, a typical diode has a voltage drop of 0.7, so we multiply by the current flowing through it. For example, if the LED consumes 30mA = 0.7*30mA, we get 21mW. The 21mW of energy will be lost as heat at the diode, which is not a problem. But if the load requires a current of 3A, the heat generated will be 2.1 watts more. Therefore, we must use a larger diode that can withstand a higher current. For some people, they may think that paralleling 5 1A diodes can withstand a higher current, similar to a resistor. It may not be a good idea because some diodes are lazy to use their friends' energy, and some diodes bear the entire burden on themselves. Therefore, we do not want this problem to occur. So we choose a higher spec and use only one, which will be better. Thank you to all friends who follow and watch. Thank you for information from the Internet: The Engineering Mindset