Parallel port Isolation

[xtal]

Here's an untested parallel port isolator ...
I',m planning to use it with HobbyCnc Pro driver board
Will use 4-pin isolators from Jameco
Most resistors are vertical with 1 end voltage bussed to pcb

Does anybody see any problems with layout/ciruits

The zip file is the expresspcb file

[kfong]

You should have both power supplies isolated. Here is one we designed.
http://www.embeddedtronics.com/opto.html Circuit posted.

Kin

http://www.embeddedtronics.com/

[xtal]

Why do you onlly isolate 12 signals instead of all 17...

I would think that the ones not isolated would pose a bigger
danger than step/dir... signals....

[kfong]

For CNC application only the ones needed are isolated. The non isolated signals are only there for testing, not normally used. They don't have the terminal posts like the others.

Kin

http://www.embeddedtronics.com/