Thread: DIY 3020 CNC I/O Board
For pull up resistor calculations you must consider the current passing through the line. Most diodes require 20mA maximum, so around 15mA will be safe to work with. Based on the diagram, for a 5V supply the pull up resistor (22K) is quite high; remember that there will also be a voltage drop in the opto-isolator.
Last edited by danilo; 29-07-2015 at 08:29 PM.
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