First Look: Cheap Parallel Port Opto Isolator Board

I was looking for a parallel port optoisolator /optocoupler card, and found this one ebay.com for something like $20.

The (Photo below) card came in a few weeks, packet delivery from China.

The card came in an envelope protected fairly with few layers of bubble-wrap. Included with it were a 1 meter parallel cable, and a 2 page color instruction. There is a bit of inscrutable Chinese/English about the power supply, but I think I will get it sorted out. I suspect that it does require +5v to run. Oddly, I may power it from a modified USB cable : |

Without the DB25, the board measures 70mm x 90mm. The mounting holes are 60mm x 80mm, and will accept a 3mm screw.

The card has 12 outputs and 5 inputs, which appears to match LinuxCNC.
The screw terminals and DB-25 connector are unremarkable.

There appears to be 17 opto-isolators. I am not sure what the extras are for. I would rather the optos are socketed, rather than surface mounted as they are.

There are 2 Schmidt trigger chips, which appear for cleaning up the digital signals.

It may be a few weeks before I get a computer going to test it, but I will follow up on it here.

"There are 17 optos as it needs 12 outputs and 5 inputs and all of them are isolated."
I guess I need a little math practice : )

I drew up a 3D printed enclosure for the board. If the board works okay, I will upload the stl file to thingiverse. If it doesn't I wouldn't want to encourage anyone.

Anyway, the box is simple. It just protects the board, and gives a lot of places to ziptie wires in place so they are strain-relieved. That's what all those little slots (and the ones you can't see) are all about. The cover is printing, now.



I am still hopeful that this board will be fast enough for my machine. I only have a long-style Nema23-sized 5-phase y-axis motor to move a 3+ foot wide gantry, so I don't expect blazing performance to begin with. The motor can move the gantry at reasonable speeds and acceleration, but even with smooth acceleration at high acceleration rates, I can stall it. I left a space for an A axis. One never knows.

I used my RDL Adruino stepper utility to test the access and move it around for working on it.

Looking forward to all the axis moving at once : )

Hi Brenda,

This board can go up to 7200mm/min on 4 axis with stepper drive on 10000 puls/rev. On mach it can go up to 15000 mm/min on
3 axis with dual core pc.

This are importand value's for the board :

Nice to have a 3d printer. Do you print igus chain's also?

Grotius, thanks for the info and settings : )
Now, I someone might give me a laptop with parallel port on it, so I'm going to try that.

No, the chains were takeout. This machine is made from scrap wafer-fabrication parts. Even the wire is used : )
Though a lot of the linear stuff is NHK : )

The chain was made from two segments. I didn't have enough links for the small one, but I found 10 links on ebay for $5. : )

I will post a current pic of it this weekend.

My friend donated a Optiplex 755, with 4GB RAM, with a parallel port on the back.

Apparently, the Jitter is 43933, and 23482, and I am not getting warnings, so I hope that will run my machine.
My machine has a undersized y-axis motor, so I don't need a lot of speed.

The interval numbers are 1040093, and 48388. I don't know if that means as much?

"Most of them ..."
How many do you have?

BrendaEM wrote:

"Most of them ..."
How many do you have?

Tommy's CNC machines breed in his workshop like coat hangers in a closet!