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Thanks to all. Scroll to continue with content. Have you done any calculations on LEDs and transistors before? It is much the same The input is a LED and the output is a transistor. Forward Current. This will give you the LED voltage drop for a given current.
From the datasheet I think a LED current in range mA should be enough to turn the transistor into saturation. Go for a LED current equal to 15mA. Kind of wrong. The LED will also have a voltage drop. Take a look once more on figure 5. This will show the voltage drop versus current. Find the voltage drop at 15 mA and take this into your calculations please. Ok, looking the figure 4, at 15mA there is about 1.
I will use a trimmer instead a resistor. As regards the resistance of the transistor, which logic do i use? I would not have used a trimmer. You do not need a value that is ohm. If you feel for it use two resistors in series to get close to the value. You can use figure 2. If the opto is connected to some 5 volt logic gate or controller.
Use anything from 1Kohm to to 10K. I guess a 4. From the datasheet at page two. We see that the Saturation voltage, collector emitter will be at typical. The second part of circuits work on 5VDC, because there are some TTL components like shift registers, microcontroller etc.. Use the 4. Thanks, Roberto. Assume using figure 2 in the datasheet. The voltage drop in the transistor will be typical.
So the current in a 4. It should be easy now to get a picture of the resistor wattage. Thank you Roberto. Kind of correct. But the transistor in the opto will be more or less full on with a LED current of 15mA. Hence the emitter resistor will control the current. I do not know were you got the nA from. Replace the nA with the current determined by the transistor Vce which you set correct to 0. No need to have the transistor conducting max current. And the higher current.
The higher Vce voltage drop. By using a 4. You will have values well inside the spec of the opto. And that is also important. So stick with figure 2 in the datasheet. You have got how to calculate the LED series resistor correct. But use a emitter resistor in the range of 4. The output to the Arduino input port will be at the point named Channel II. And you will no problem at all. You must log in or register to reply here.
General Electronics Chat 0 Apr 16, Similar threads I need help with my circuit optocoupler, transistor, relay tlp triac zero crossing optocoupler Reading datasheet for optocoupler The ohmmeter shows wrong output resistance of an optocoupler in Proteus Is it valid to create your own model of optocoupler in Proteus?
You May Also Like. Continue to site. I need help with my circuit optocoupler, transistor, relay. General Electronics Chat. May 4, Apr 21, Reading datasheet for optocoupler.
The ohmmeter shows wrong output resistance of an optocoupler in Proteus. Apr 16, Is it valid to create your own model of optocoupler in Proteus?
CNY74-4 IC - 4-Channel Optocoupler with Phototransistor IC