Free Stuff by, and From Paul for YOU!

  • Dancad3d The original CNC shareware program!
    See Below For Updates

    09/03/03- Chopper Stepper Drive:

    Right click on link and select "save as"

    L297/298 cutting files in Dancad ASC format>

    L297/298 layout of components.JPEG.

  • NEW! Alan Garfield's L297/298 Layout"

    ...And an HPGL toolpath file I adapted from a TIFF for PCB engraving.(in ZIP format)


    Larger, easy to read UCN5804 translator and power amp.JPEG.


    Layout of the L6506 Current controller from STM, will work with uni or Bi-polar. Phases in, phases out PWM'ed.Very simple, a little logy with darlingtons, works better with IRL540's. Pull down the gate with a 10k 1/4 w to common, shuts off faster.

    L6506 layout.JPEG.

    L6506 board photo.JPEG.

    L6506 Data Sheet.PDF file.

  • 04/02/03-Stepper Motor Controller. Here is the secret of the UCN5804 stepper driver chip.



    The 5804 is a full/half step driver with enable input, drives at 6-30 volts at a maximum of 1.5 amps. Pretty insignificant, right? WRONG! The 5804 has open collector outputs; you run 5 v. into the chip, then pull up the outputs with a 2.2k 1/4 watt resistor. You pipe that into a 7414 schmidtt trigger to clean up the pulse, and run the output of that thru a 1K bias resistor to the base of a TIP 122 power darlington. Voila (cello?), a high powered half stepping driver. UPDATE:04/07/03 Here is the best I could do on short notice, I just changed computers and most of my stuff is on the other one.Eventually I will have the cutting paths available for download as *DXF or *PLT files.

    This is a scan from a file copy I kept. For the sake of those who want to tinker, the chip on the left is a ucn5804, the chip on the right is a 7414. The connections on the left from the top down are :






    full/half step,


    The outputs on the right go thru a 1K bias resistor to a tip 122 or whatever.I have a chopper unipolar board that goes with this that will be put up on here eventually.The pullups are all 2.2K,1/4 watt. I know Newark Electronics has the 5804, and quite a few other vendors do, also. I came up with this design in 1989 from a suggestion by Dan Hudgins of Dancad3d,but I have never seen it or anything like it on the Web. The half stepping is very smooth, and there is no limit to the power you can put out, just use more powerful transistors. I have used MJE3055T's, tip 102's, tip122's, IRL540's, etc.They all work for output transistors.Current control can be a large resistor or whatever you want. I have used a 3524 pwm chip, a L6506, and a LM339/7409 combination.

    .....And here is a picture of the board.

    Here is an old design of a board based on a NASA design (see article)

    For bias resistors I used 1K 1/4 watt, for transistors I used tip 102's. A 2.4 ohm 20 watt resistor serves as a current limiter.

  • Slo-Syn motor conversion to stepper:

    I dug around in my box of old projects and came up with a modification I had forgotten about: converting a BIG slosyn synchronous motor to a stepper. These motors will take 90-100 volts easily and produce up to 750 Oz-In. of torque. The only drawback is they are slower than death. They can be bought from places like Surplus Center(Item 10-990-A) The Phone # is 800-488-3407

    PS Yes, you can use them Bipolar, I checked it out with the L297/298 chopper combo, they work great. Here is a current controller (Linear) based on Jean-Charles Vachon's design at Mel Bartels Astronomy site.

    Note: This picture has been removed because I received an irate email telling me that I should be more specific and put generic values, etc, part sources,blah,blah,blah. I don't need grief like that so I have a new policy: whenever anyone doesn't like the way something free looks,fine. Kiss it goodbye. Less free stuff means less irate emails.(PS: I answered all the emails questions politely,by the way.)

    Since I am maintaining a freebies page, I am hoping to offer all the designs I no longer produce commercially; these include an L297/298 chopper board, an L6506 unipolar current controlled board, several Basic Stamp2 breakout boards, SCR speed controls, and Bob Blick's H-Bridge, amoung others. I may also have some Shareware and Abandonware. This page is under construction...check back soon.

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