5v supplies for breakout board

[cropwell]

The purpose of the opto isolator is to prevent any damaging voltage getting to the I/O pins of the LPT port. You could connect directly from the port to the driver, but it is risky. If you get computers cheaper than decent BoBs then it might make sense to wire directly to the driver. 5v from the computer usb port should only provide power to operate the output pins from the computer. Take no notice of the Line designations, that is only relevant for printers, but the output pins(->) should be isolated with 5v power taken from the computer. The input pins (<-) should be isolated with their 5v supply taken from an external supply.

In the end most things will work, but the risk factors are different.

Cheers,

Rob

And Seasons Greetings to all who sail in her.

[EddyCurrent]

This is what I used; http://www.rapidonline.com/electrica...sp10-5-51-4682