CNC router is made from two old printers and old CD player. I used
parts that I found in the basement, I collect a lot of electronic
and mechanical things that I find out the garbage or on the internet.
I made the electronic from passive components. I did not want to use
microcontrollers because it is not easy to obtain them here in
Croatia, there is only PIC to buy here and they are very very
expensive here. All 3 drivers for stepper motors is made of two IC
and output power amplifiers that provide power to motors. CNC
electronics is designed for unipolar stepper motors.. I had only one
unipolar and bunch of bipolar motors, I had to open two bipolar motor
and connected to the coil middle wire to motors become unipolar motors
that I could work with them. Schematics is a very simple and made from
standard parts that can be purchased at any electronics store.
The only thing you need is a CD-4516 which is CMOS up / down counter
and a CD-4028 BCD-to-decimal decoder and its output is connected to
power amplifiers for the motors. Software is the Mach3, and he directs
the signals to the parallel port, you need two pins for one axis.
These pins are step and direction, step determines the speed of
rotation of the stepper. Up / down counter and BCD decoder divides the
signal into 4 pieces for controlling motors. So there is no need for
Microcontrollers! And I made 3 stepper drivers for each axis and plug
it into my computer and configured Mach3 for pins.

Electronics cost me about $ 20 so you do not get rid of old printers,
but make your own CNC machine with three axes, can be a mill, lathe,
plotter! Enjoy video! You can use any CNC software, like EMC for linux



P.S.  I have no idea who is the author of drawn picture, i just downloaded it from devart..

[UPDATE] October 2nd 2011

Unfortunatly, i dont have time so i made schematic, do everything that is inside schematic and
it will work!

here are links to schematic:

http://imageshack.us/photo/my-images/16/23690976.jpg/

http://i54.tinypic.com/2qa8w8w.jpg

http://postimage.org/image/yrk5ehqc/

You can use up to 32V so it's not only for 12V, and one more thing this schematic is based on Tom McGuire's schematic, i aded few things to make it work because direction pins didn't work on his schematic, so this will work without any problem!

If you have any questions, comment!