ON 20051017@10:27:53 AM at page: http://www.piclist.com/techref/io/stepper/linistep/faq.htm#38641.8981944444 James Newton[JMN-EFP-786] Replied to post 38641.8981944444 |Insert 'The caps do a very nice job of smoothing out the high voltage pulses and the remaining juice leaks off quickly.' at: '' I have a question about the Linistepper. There appears to be no protection for the back emf generated by the motor coil when the drive is turned off. It appears to me that the voltage on the transistor collector will rise to a fairly high value and be in danger of destroying the transistor. Obviously this does not happen, perhaps the caps on the base drive limit the dI/dt sufficiently? I am curious if you have ever looked at the voltage waveform on the transistor collectors. If nothing else, the current would take longer to decay on turn off than if it were shunted with a reverse diode, or even better, a zener, that clamps the back emf to say 50V, before it can pop the transistor. This current would tend to reduce torque as it is opposing the rotor moving to the next position.

By the way Linistepper is a great piece of work, how to do a lot with very little parts.

TomH sarnidac{AT}bigpond{DOT}net{DOT}au ON 20051017@10:40:29 AM at page: http://techref.massmind.org/techref/io/stepper/linistep/faq.htm#38642.1569560185 James Newton[JMN-EFP-786] Published and replied to post 38642.1569560185 by akrooke |Insert 'It's a good question... Sadly, it is almost impossible to answer. There are so many things that affect the actual torque output of a stepper motor that estimates are useless. You just have to try and adjust motor size as needed. The actual torque or a specific motor/driver/power supply combination can be measured but is very difficult to guess.

Take a look at the stepper page and the torque page for more general information.

There is an automated tool at http://www.galilmc.com/support/motorsizer/index.html which proports to answer this sort of question. You put in system type, load mass, etc... and it tells you want motor and drivers to use. Does require registration. And that is specific to thier motors and drivers.' at: '' akrooke@ntlworld.com asks:

How large a stepper motor would you need to use to drive the steering gear of a small ship, producing about 400KNm? Sounds ludicrous I know, but I was just wondering.

|Delete 'P-' before: '' but after: ' Hello, can the linistepper be upgraded by the use of FETs of higher power? I'm looking at steppers with 4.6v 2.5a per phase, and 300inlb.

Thanks for your time.

  • ' ON 20051024@9:58:33 AM at page: http://www.piclist.com/techref/io/stepper/linistep/index.htm#38646.8730092593 James Newton[JMN-EFP-786] Published and replied to post 38646.8730092593 by Barnburn |Insert 'Certainly, however the engineering of that is left "as an excersize for the student." There is some information available at http://www.piclist.com/techref/io/stepper/linistep/lini_tun.htm' at: '' Barnburn@wi.rr.com asks:
    Hello, can the linistepper be upgraded by the use of FETs of higher power? I'm looking at steppers with 4.6v 2.5a per phase, and 300inlb.

    Thanks for your time.
    |Delete 'P-' before: '' but after: '