Hi Mariss
I know this is an old topic, but I want to ask you a question about your setup for 3.3-5V, compared to the one PMinMO uses in his opto board. I think yours is better, only not sure why.
The other setup is:
5V (USB port), anode of opto-LED, 470 Ohm resistor, pin of the parallel port. There is also another 2k2 resistor between the parallel port pin and 5V, I guess to avoid conduction of the opto-LED with the 1,7 V difference, in case is a 3.3V port.
Which one would you use?
Thanks
Rafael |