And here I've put together a circuit that I think is the absolute cheapest and easiest way to control stepper motors with step and direction signals. It works with many of the free or low cost softwares that produce step and direction signals through the parallel printer port.
I'll explain how it works but for those of you who just want to get on with it This way you can easly correct any mistakes and try different things. This schematic is just to control one motor so for the milling machine you need 3 of these circuits and 3 motors. From Left to right and top to bottom. I try to draw schematics so that positive voltages are toward the top and ground or negative volge is toward the bottom. Inputs are to the left and outputs to the right.
Fist off the voltage that you are going to use to run the motor needs to be stepped down and regulated for the logic chips. I used a 6. So the resistor R1 drops the voltage, the Zener diode regulates it to 6. One signal from the printer port will tell the counter if it will count up or down and the other signal, called step, will increment or decrement the counter by one count. Now were only going to use two outputs from the counter Q1 and Q2. With this binary counting method there are only 4 combinations of output from the counter: 00, 01, 10, and These lines are fed to the A and B inputs of the other IC CD which decodes these combinations to 4 seprate outputs.
I did a trick here using the C input to work as an Enable input. If the Enable optional is connected to the parallel port and the computor tells it to shut off all of the outputs to the FETs will go low Off. Now everybody wants to know what the light bulb is for.
Its not so much whether you use a bulb or a resistor, its that a bulb comes with a socket. You can get these wedge base light bulbs from 1 watt to 20 watts. Start with may be a 4 watt bulb and if you find you need a little more beef you just pull it out and put in a 10 watt bulb. It's really handy. And I found it's good to have some voltage drop there as kind of a ballast for the motor windings. The diodes catch some of the current that comes out of the motor each time the FET transistors turn off.
The diode feeds this current back to the supply. When you get the circuit up and running find a power supply that puts out more voltage than you really need and then change out light bulbs till you get it running smoothly. Some of my stepper motors are 5 or 6 volt and some are 12 volt but it all works out. OK here's what your all looking for. I made a simple PC board layout that includes 3 motor driver circuits connected to a 25 pin D sub Parallel printer port connector.
Here's a picture of the layout. At the top of the picture you see a place for a voltage regulator. You can use that or you can put a resistor and Zener Diode in its place like the schematic shows. On the right edge is a place for the 25 pin D-sub connector that connects to the parallel printer port.
You just jam the PC board between the two rows of pins and solder it. On the left side are places for the lamp sockets. You need to look over the schematic to see where some of the parts go but it's all there. If you have a time machine you can go to the future and ask yourself to make the circuit board with the finished machine and then bring it back and finish building the machine. After a couple of tries I got the board to come out pretty good.
The machine routes what are called isolation paths which means it seperates the copper that is associated with a conductive path from all the other copper around it. This leaves some areas of the board that are not associated with a path still covered with copper.
You could leave this extra copper on there but when your soldering it is easy to get solder bridges across the isolation paths and short circuit something. Most of the tutorials on this site are created in response to the difficulties I see users having with machines mechanics, structural dimensions and the electronics that drive their CNC machines.
Overwhelmingly, I have noticed the electronics pose the most difficulty with new users. I have put together another set of wiring instructions that demonstrate a methodology that begins with a simple and straightforward wiring of only one driver and motor and follows with the remaining drivers while testing throughout.
The steps per inch for many forms of mechanical option are also explained in depth. I thoroughly explain the wiring of the power supply, an optional 5v power supply to provide a 5v digital supply to the parallel breakout board. The wiring of the parallel breakout board from the output terminals to the driver digital pulse step pulse and direction lines are explained.
The new parallel breakout board appears a bit different, but the process of wiring and testing is the same. Go to the new parallel breakout board to get more information and the wiring diagram. Beginning with only one driver and motor eliminates most of the complexity that typically scares the timid folks out there. But first, the power must be establish.
The electronics require two forms of power: the high current and high voltage DC power for the motors and the low DC voltage power for the signals. In these videos, the motors are being fed by 36 volts and a max of 8.
However, various levels of voltage and current can be used. An explanation of the requirements of motors and drivers will be explained in a future tutorial.
The main power supply is dedicated to maintaining a constant 36 volts and permitting a maximum of 8. The main line from the wall is connected to the neutral, live and ground connections on the power supply.
The breakout board requires 5 volts of power to condition the signals. Signals are received by the parallel port as inputs and are sent from the breakout board as outputs. Outputs are generally to control the motors, router operation, coolant operation or various other machine peripherals. The latter is outside the scope of this tutorial as this is aimed to get the basic electronics established.
This 5 volt power to the breakout board can be sourced using a couple of methods: a wall adapter, small power supply, or USB power. All of these supplied must by rated for at least milliamps or.
This power is connected directly to the breakout board's 5 volt terminal, EN terminal and the GND terminal. After the power supplies have been properly connected, the output of power should be tested to determine if the correct voltage is being produced.
A standard multimeter can be used to test the voltage from the power supplies. The breakout board in next in line to be connected. Simply bend the leads over to fit the PCB holes typically. Trim the leads. Install 7. These have NO orientation.
Orient the dot with the PCB silkscreened dot. Spread the leads apart to fit the PCB holes. Do not confuse with CC Install P1 DB25 Male connector. Take your time as many pins are close together. We also solder the mounting lugs for an even more robust mounting. These may require a little extra heat to flow the solder as a lot of copper is present. Orient the tab towards R The PCB silkscreen shows this as a wide white band. Install the LM U5. Insert the U6. Orient the tab towards C6.
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