Hi,
I am having a weird problem i cant figure out. I am trying to optically isolate a computer from arduino. So i got an arduino nano and a usb2serial for arduino. However when i connect the tx pin form any of those to an optocoupler the voltage of the tx pin drops from 5v down to 1.25, 1.33, depending on the value of R1 (see image). The optocoupler does not open at that point given that the forward voltage for the diode is not reached.
I am quite baffled,
the optocoupler is HCPL 2201, it is working properly I tested it.
In a test connection like the one from the image, the current passed through the input stage is about 20uA, where it should be around 3mA.
I tried posting this question on Arduino forum however I got an answer to "Look up ohm's law", so yeah, got agitated, and decided to come here to ask people that actually know something.
I am having a weird problem i cant figure out. I am trying to optically isolate a computer from arduino. So i got an arduino nano and a usb2serial for arduino. However when i connect the tx pin form any of those to an optocoupler the voltage of the tx pin drops from 5v down to 1.25, 1.33, depending on the value of R1 (see image). The optocoupler does not open at that point given that the forward voltage for the diode is not reached.
I am quite baffled,
the optocoupler is HCPL 2201, it is working properly I tested it.
In a test connection like the one from the image, the current passed through the input stage is about 20uA, where it should be around 3mA.
I tried posting this question on Arduino forum however I got an answer to "Look up ohm's law", so yeah, got agitated, and decided to come here to ask people that actually know something.