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View Full Version : Need Help! 5V OPTO Supply



dff427
09-11-2008, 01:48 PM
Pin 14 on my parallel port is putting out 4.8V when it's not connected to my controllers. When I connect it the voltage drops to 3.1V. I can't get my stepper motors to do anything. I assume this is why. I've ordered a breakout board that steps the voltage up to a solid 5V. Is this a common problem?

My power supply is putting out 28V. I tried connecting the 28V to 4 controllers in parallel thinking it would be split to 7V per controller. It didn't split and I was hitting each controller with 28V. I didn't hear or smell anything. I wonder if I've damaged the controllers?

Any help would be greatly appreciated!!

budP
09-11-2008, 04:44 PM
The first thing I would advise you to do is to read the documents that came with your controller. Secondly learn a little about series and parallel circuits.
Your steppers are probably 3 or 5 volt steppers and they are run on 7 to 10 times the voltage they are rated at.
I don't know why you are hooking up your board to pin 14 this makes no sense at all.

budP

irving2008
09-12-2008, 11:07 AM
Pin 14 on my parallel port is putting out 4.8V when it's not connected to my controllers. When I connect it the voltage drops to 3.1V. I can't get my stepper motors to do anything. I assume this is why. I've ordered a breakout board that steps the voltage up to a solid 5V. Is this a common problem?

My power supply is putting out 28V. I tried connecting the 28V to 4 controllers in parallel thinking it would be split to 7V per controller. It didn't split and I was hitting each controller with 28V. I didn't hear or smell anything. I wonder if I've damaged the controllers?

Any help would be greatly appreciated!!It would be unusual to use pin14. Convention is pin 2,3 X step/direction, 4,5 Y step/direction, 6,7 Z step/direction

Without seeing how you've wired everything and what drivers you are using its hard to give an opinion.

Pin 14 is an output, 4.8v unloaded, 3.1v loaded is right. Pin 14 on its own wont result in anything working!

Re the voltage... parallel drivers will see the same voltage, but the current pulled from the power supply wil be the sum of the currents drawn by each driver.

Torchhead
09-17-2008, 08:25 PM
You are tying to run external electronics off of a logic pin. The source of +5 to run your drives (logic or opto inputs) needs to be a solid source of +5, capable of providing several hundred millamps. Most higher end BOB's have an auxillary +5 power supply on the card. The parallel port on a PC has no +5 power connection. The USB and Game ports do. You can also tap into the PC's power supply directly off one of the unused power cables like plug into devices like hard drives and CD/DVD players.

PTtec
09-18-2008, 04:30 AM
i don't think that is a good idea cathe the 5V from the others plugs, and the 3,8v that the parallel port give should be good with a smaller resitor(not to small make the calculations, and a LED is a diode but not of 0,6V...more 1v-1.2v)
and the sorce of 28v for the servos in serie.... can not be a very good idea...