[tranceamerica]

Hello,

I've gotten a couple of vexta motors, and am working on designing some simple interfaces so I can play with the motors using my computer printer port.

I've found some schematics in "The Robot Builder's Bonanza" that describe how to build an "experimenter's interface" (which I interperate as a buffer between my computer and the stepper driver board) and a "stepper driver board"

there's also a schematic to put in power resistors and transistors and diodes, so I can provide more power to the motors than can be pulled through the driver board.

Ok, so far, so good. Here's my questions:

1) the buffer board is 5 volt, and the driver board 12 volt. The motors themselves are 12 volt too, but elsewhere on this forum I've read that the motors want much higher voltage than they're rated at. So, if I provide 5 volts to the first set of IC's (buffer board) and 12 volts to the second set of IC's - will I fry the first set of ic's? I imagine that the transistors seperate the power for the motors from the rest of the driver circuit. Isn't a IC a set of transistors, so it will also seperate the power?

2) I know sorta what resistors and capacitors do - but I don't have the foggiest idea how to size them. These schematics don't show a single capacitor, but I thought I needed to provide some small capacitors to smooth voltage at some places. Where might one put a cap, and how do I size it? Seems like this is missing from the design...

Also, in terms of resistors - I'm putting them in two places:

a) with the indicator led's (for testing, to show my stepping, etc, they just light up to show me if I"m sending the right info from the computer...) The led's will be on 12 volts - but they are probably 5 volt leds. Can I size a resistor such that I don't fry the led's? How do I do that? I've got some 1/4 watt, 330 ohm resistors (recommended by the text) but I have no idea if they are anywhere near the right size.

b) between the flip flop outputs and the power transistors. these are 1 watt, 1k ohm. I don't quite get what these do - I thought the high power was supplied on the other side of the transistor, so the resistor seems to be on the low power side. I don't get it. Still, how do I size these properly? The text seems vague on this point.

Ok, I'm sorry my questions are so basic and vague. It's important to me to understand this stuff - I don't want to simply buy a driver board, I want to design my own so I can learn all of this stuff. Maybe someone could recommend a simple book about simple electronics design, or point me towards a good website.

[Al_The_Man]

I don't want to simply buy a driver board, I want to design my own so I can learn all of this stuff. Maybe someone could recommend a simple book about simple electronics design, or point me towards a good website.

The 'Learn' comes first then the 'Design' I would suggest searching the web for basic electronics and simple logic circuits, get yourself a bread-board and a power supply and learn the basics building logic circuits this way in conjunction with a good Electrical/Electronic book on basic theory & one with Experiments, there are lots out there.
Also there are kits that you can learn with from the Nuts & Volts site etc.
http://www.nutsvolts.com/PDF_Files/stepper.pdf
Once you have mastered the basics, there is also the world of MicroChip processors that have a site that has all the circuits and code to program your own controller etc.
I would suggest not involving a PC yet, until you are confident you know enough to interface to it.
Al.

[tranceamerica]

Ok, when I said "design" maybe I should have said "build someone else's design so I could learn something".

I know I shouldn't torch my pc for fun, but it's an old one that I'm dusting off for just this purpose. It's not in use anyway.

Anyhow, I'll get a book or two to answer my questions. Thanks.

[pminmo]

Look at my website http://PMinMO.com circuits and copper you can build.