Reply with QuoteThat would be good. Then I can subscribe to the build log without having to hunt it down. I'm always interested in following Linistepper projects. Thanks.Originally Posted by epineh
Chris
Good question, the lathe is a small "shop made by apprentice" type but it is a metal lathe. On the other hand it will only be used for wood turning, I have a specific purpose for it and it won't touch a piece of metal on anger.
I guess either the general metalworking mill/lathe project log or the wood lathes/mills.
May have to toss a coin. I can post a link on this thread if ya want. I have almost finished the electronics enclosure but not much done on the lathe itself which is why I haven't started the build log.
Russell.
That would be good. Then I can subscribe to the build log without having to hunt it down. I'm always interested in following Linistepper projects. Thanks.
Chris
No Probs, the drives are all tested, Pwr supply finished, cooling fans are going, just have to mount the motors onto the lathe, I will post a link on this thread once I start the log, which will probably be in a weeks time.
Russell.
I have started a build log for the lathe, here is the link :
http://www.cnczone.com/forums/showth...909#post398909
Russell.
trebby, the linistepper is designed to be connected directly to the parallel port data pins for step and direction control. I know the kit that we sell works just fine with direct connection assuming the power supply is isolated and the board ground is connected to the PC ground. I can't speak for the board that posix is sharing, because I've not tried it, but it looks ok to me. Anytime you connect anything electrical to your PC, there is a small chance of destroying the computer. This is especially true with hobby stuff. Try an old PC first?
As to #4, I have no idea as I didn't make that schematic. Posix will have to answer. As OCNC indicated, the Linistepper design is fully documented at
http://www.piclist.com/techref/io/st...step/index.htm and all the terminals on the schematics you find there are nicely labled.
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Last edited by aferrier; 02-19-2008 at 09:41 AM.
Hi... I'm a noob to this forum. I've been building a couple of revisions of the LiniStep.
I've successfully built the "posix" design board and have my LaserJet motor whirring very smoothly. I've noticed that this design has two additional 470 ohn resistors linking +5V to each pair of power transistors... these don't exist on the "original" schematic design. Would anyone know what they do?
I've also tried making the "salvado" version of this board beacuse I liked the voltage regulator and transistors at one end, but couldn't get it going... just low-power pulses to the motor that barely turn it. So frustrated in my debug, I decided to make another board and build another with new components... same exact symptoms (I ultimately need 3 boards anyway). All I can see in difference in design are these two 470 ohm resistors.
Any ideas anyone?
Many thanks,
Alistair
Those 470 ohm resistors help push the drive transistors to saturation (q1,2, 3,4), that current is stolen by q5,6,7,8 when the drivers are supposed to be off. I believe their size needs to be coordinated with the other pic driven resistors if you use micro or mini stepping. I have reduced them to 95 ohms (120 ohm in parallel) and they are working good for full step at 4 amps with different drivers (TIP142). BY ALL MEANS IF THE CIRCUIT IS THE SAME, the 470's are vital for some of the stepping scenarios.Hi... I'm a noob to this forum. I've been building a couple of revisions of the LiniStep.
I've successfully built the "posix" design board and have my LaserJet motor whirring very smoothly. I've noticed that this design has two additional 470 ohn resistors linking +5V to each pair of power transistors... these don't exist on the "original" schematic design. Would anyone know what they do?
I've also tried making the "salvado" version of this board beacuse I liked the voltage regulator and transistors at one end, but couldn't get it going... just low-power pulses to the motor that barely turn it. So frustrated in my debug, I decided to make another board and build another with new components... same exact symptoms (I ultimately need 3 boards anyway
Any ideas anyone?
Many thanks,
Alistair
thanks all of you for designing and updating the linistepper.
iam following posix made epineh modified linistepper layout.i am trying to make professional board.once i get them i'll populate and test them.
mean while i have a doubt.i'll be mounting all of them(3 boards) on one big heat sink.so is it ok if their grounds(TIP122) become one.i can place a insulator in between them.still i wanted to know what will happen if their grounds get shorted.
and isn't possible to adjust the current using pot and a resistor combination? like in L297+L298 where we see reference voltage and adjust the current accordingly.
my motor is rated at 0.95,so i placed 2 1ohms resistor on board.and it felt like current is low.bcz i can stop the motor if i hold it tight.i need more torque.(i powder the board using 12v supply and use ATX supply.)
If you short the transistors, they will blow up.
Yes, you can use a pot to fine tune the current, but it must be a high power POT, just like the high power resistors.
You didn't say what voltage your motors are rated at. You should use a power supply that is more than the rated motor voltage; up to 2 or maybe even 3 times. If your motors are rated below 1 amp and 6 volts, that is only 6 watts of power... you /should/ be able to stop a 6 watt movement with your hand. No driver will make a difference with that. Get a more powerfull motor (e.g. 2 amp 6 volt or 1.5 amp 12 volt with 24 volt supply) and you will have better luck.
By the way, you do know there is a very nice professionally made PCB already availble for less than anyone could possibly have one made? They are available for 3 for $35 at
http://www.piclist.com/techref/io/st...index.htm#kits and there is a kit with all parts at that same page for $35 each or 3 for $30 each. Each board is 1 axis, but there is no reason you can't hook all 3 to one heatsink.
thanks for the reply james.
abt placing all the transistors on one heat sink,seems a bad idea.so shld i place a separate heat sink for each transistor of a board?
all i wanted to know is,if i place a board on one heat sink,whech has 4 TIP's,their collectors will get short.so is it ok?
and iam using 3 motors.2 rated at 4V@0.95A and one 4v@1.3A
i think i'll go for higher voltage.now iam using 12v.so may be 24v will solve my problem.
and can't i just use a 1Ohms-5watt resistor and a small trip pot combination to get the required current setting?
I don't know how to be more clear on this: If you short the transistors together, they will blow up. The kit I supply comes with mica isolation spacers and washers to keep the mounting bolts from contacting the heat sinks electrically.
The supply voltage should be at most 2 to 3 times the rated voltage of the motor. With those tiny little 4 volt motors, your 12 volt supply is already more than they should be getting. Again, the issue is that they are tiny motors. Nothing is going to make them stronger.
The current that flows through the 5 watt resistor will also flow through the trim pot. If it isn't rated to drop the watts, it's going to melt. Ohms law is a law.
another question,
can I insert PIC16F84A to Pisox's PCB ??
because may be I can only programe PIC16F84 now
i got it.thanks.those mosfet shouldn't have single ground.i ordered some mica spacers along with plastic screws.bcz if i use metal one,i might short the collectors.
below is the pics of my motors(some guy posted it.thanks)
http://www.cnczone.com/forums/attach...0&d=1192411595
http://www.cnczone.com/forums/attach...2&d=1192411595
i ran these before with L297+L298 combo.and they did well.but it was in bi-polar config.i know bi-polar gives more torque than uni-polar.
I tried both A and non-A versions of PIC.both worked well.
@James Newton
sorry for bothering you again and again.
i couldn't find any motor which is abt 1.5 to 2A current rating.
but i have some whose rating is 3.6v@2.9A.i know i can't run these at 2.9,as the linistepper is not capable of it.
but what if i run the same at 2A.it will give me low torque but at least it will give me more torque than previous one.
so can i do like this?
and say if i use power transistor like 2N3055.can i pump in more current?
Man... its a big mess.
at last i found out the issue.
It was the resistor i used (1 ohm-5watt).but when i measured it.its showing 2.5ohms.so i bought 2-0.5ohms resistor and tested the motor and board.
it worked well.the motor was drawing 1.8A(motor is rated for 1.3A per phase) and the torque is ok.(better than previous)
and i mounted the TIP's on a really big heat sink.(i tried IRLZ44 but the didn't work.i guess pin config is same as TIP)
i'll try much lower values of sense resistor.i know min possible is 0.6ohms as per the tutorial.but what worse could happen?motor will run hot.as stepper is designed to run at 50-90 degree,it is ok for me.it is lot better than L297+L298.
My Heat sink is 4''X12''.so iam planning to mount all the TIP's at equal distances and will use pulgin type wires to make contact with the board.
You can run any motor that is rated higher than the current you put into it, and probably you can get away with "overclocking" a motor a bit as well, as you suggest. It might burn out the motor, but that is the risk you take.
You can "beef up" the transistors on the Linistepper to manage more current, but heat will be the limiting factor. You can only move so much heat away...
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