is there any reason i can [sic... can't ?] just purchase the big blue box with the five pins and hook it up directly myself instead of using the module?
so what i am gathering the jumper "on" disables isolation between the input pins and vcc?
As said, if you want opto isolation, then remove the jumper, use external relay power, and don't share grounds.
i would need to remove the jumper? and connect the vcc to a more sufficient 5 volt power supply.
I don't think separate grounds are possible with this module - they're tied together on the board. I suppose cutting the trace is an option....
so arduino's 5 volt pin is not sufficient power for the relays vcc? so to use multiple relays, i would need to remove the jumper? and connect the vcc to a more sufficient 5 volt power supply. then trigger the inputs with a digital write? and my separate 5 volts is safely separated from my input pins?