Bill of Materials for 7x10 CNC spindle & X axis controller

For a different stepper, change the power resistors to match your current requirements.  Ohms law: I=V/R  (volts and ohms). P=R*I^2 figures the power dissipation of the resistors.

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QTY	ITEM				VENDOR P/N

4	N-channel power MOSFET (100W)   Digi-key NDP6060-ND
3	Small signal NPN transistor	Radio Shack 276-1617
2	Rectifier diode			Radio Shack 276-1661
2	5600 uF electrolytic cap	Digi-key P10265-ND
2	6V 3A CT transformer		Radio Shack 276-
2	SPST 10A relay			Radio Shack RSU 12131561
1	DPDT 8A relay			Digi-key PB295-ND
1	12V power supply		-
3	1k resistor, 1/2W		Radio Shack 271-1321
4	10k resistor, 1/2W		Radio Shack RSU 11346061
8	1 ohm 10W power resistor	Radio Shack 271-131

NOTES:

- It's a good idea to fuse protect the main AC bus, just in case.

- Shield the cable running to the stepper from hot chips with stainless braid or aluminum tape.

- The 12V supply only has to source a few milliamps.  A battery would be fine.

- This X axis circuit is designed to run a unipolar motor.  I never had satisfactory results running a homemade H-bridge setup, so if you're headed that direction I humbly steer you toward buying a commercial driver as I did.

- Peek at the parallel port connector on your computer.  Pins should be numbered, or you can download pinouts on the internet.

- Optionally, you may wish to include anti-spiking diodes across the relay and motor coils.  I haven't, but supposedly it improves life and reliability.