A few weeks back one of my customers contacted me about a Piker he was building. He was complaining about all the wiring and parts. He wanted to know if there was a simpler controller with less parts he could build. He wanted to know why I used two chips instead of one. I said you save a dollar per axis using the 7474 and the 7486 instead of some other single chip. He said he would be willing to pay the extra dollar per axis. Then it hit me! He was wiring a Piker using the schematic that comes with the plans. I though he was wiring a Piker circuit board!
At that very same time I was trying to use the L297 chip in a super simple chopper design. The L297 is made to go with the L298. You can use it to build a UniPolar chopper controller but you have to add a 7409 for each axis. I was trying to reduce the part count. During my tests I realized a L297 could be jumpered to produce a simple UniPolar controller with very few parts. There are other chips out there but their outputs need conditioning before they can power external drivers. The L297 has TTL compatible outputs. Now! I could hook FETs to the output of the L297 and eliminate four resistors per axis. Instead I am using resistors Tip120 transistors and output diodes. I know the Tip120 has a build in flyback diode to protect the Tip120. My output diodes prevent a braking action caused by the counterEMF voltage running to ground through the winding that just turned off. If you use FETs the circuit will not run motors as fast. You can't do the diode trick with FETs! It may work for awhile but at some point the FET will blow. Try it, maybe you will be lucky!
So what is Perf-X 3X ? Perf-X is a scratch built 3 axis CNC controller with two relay outputs, three home switch inputs and one pause. (EMS) Runs 5 to 6 volt 1 to 1.5 amp 6 wire UniPolar motors at 240 rpms (12 inches per minute with 1/4-20 threaded rod) with a 12 volt computer supply. This project is offered for scratch builders looking to build a simple CNC controller that is powered using an old PC supply. This is a cheap, simple UniPolar controller you can build. It is built by you using Perfboard and pretinned bus wire. The Perf-X booklet is a step by step guide to wiring your own controller. The booklet is 15 single pages so you can lay them out as you are building. Each page has only a few wires added at a time with text.
Please Read This!
This project is for Real Men who build from scratch. It does not come with any support. At $23 there is no profit for me. The $23 pays for my design time,printing and shipping time. There is no motor selection or setup help. No NEWBEs or Want-To-Bes Please! Plans cost $23 and they are only sold to the US and Canada!
Email: John a quick question
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