Jan 4, 2020 · This 3.7 VDC is fed to the input of optocoupler PC817 pin 1 and 2. On the output, I wanted to read the high and low through an Arduino connected to pin 3 and 4 of the optocoupler. I was planning to pass in 5 VDC from the Arduino to one of …

Perhaps your friend is comparing the photo transistor-output PC817 to the type of opto coupler that has an logic output type IC or a photodiode driving a transistor on the output. For example this one. They're typically specified in Mbaud and are more suited for high speed logic signals.

The PC817 has a reverse voltage rating (V R) of 6 V, so it would blow up. You could instead use the PC814, which has similar characteristics, but an AC input with two antiparallel LEDs: Alternatively, just put a diode like that in the front of the PC817. (Then the output of the PC817 would switch on only every second half wave.)

May 20, 2022 · PC817 is more suited for isolating PLC inputs and that sort of hundreds of microseconds to millisecond response isolation. For 400kHz, forget about using the PC817. \$\endgroup\$ – Spehro 'speff' Pefhany

Oct 2, 2022 · Each PC817 opto-isolator is controlled by a GPIO of ESP32. The ESP32 is powered at 3.3 V while the relay circuit is powered at 5 V. The board is powered by an external 5V power adapter with nominal output of 2A; 5V to 3.3V conversion is done on the board by a MP1584EN step-down converter such as this one .

Jul 17, 2015 · I am using PC817 opto coupler. I want a 3.3 output voltage. In its 1st pin I am giving 12volt and 2nd pin is gnd. I have connected a pull down resistor on 3rd pin. But i am confused because when I am giving 3.3volt on 4th pin, and I am checking output from 3rd pin which is 1.5volt. How can I get 3.0 - 3.3volt output on 3rd pin.

Jan 29, 2020 · In schematic 1, the relay is triggered using PC817 optocoupler. In schematic 2, the relay is triggered using MMBT3906 NPN transistor directly. Schematic 2 Which is best approach in terms of reliability and safe circuit. What are the pros and cons of both approaches?

Oct 12, 2022 · With these parameters, you can estimate the R2 value in the network SENSOR_OUT, R2, PC817 pin1 of your drawing. Take the typical forward voltage of 1.2V and the current of 20mA. This resistor is required if your sensor can sink current too great for your optocoupler and you should constrain the current to the values specified in the datasheet ...

Apr 27, 2021 · This is the optocoupler(PC817) I used and this figure is Current Transfer Ratio vs. Forward Current. There are my questions: 1.) How to decide the CTR value, because the forward current will change when the circuit is in the closed-loop control.

Jun 10, 2024 · I want to drive a MOSFET (IRFZ44N) with an optocoupler (PC817) to control the brightness of an 50 W 12 V LED. The PWM is generated by an ESP8266, 1 kHz. Following schematic is used: In general it works, but PWM set to 10% does not result in 10% brightness of the LED. I expect it be much darker.