Newsgroups: comp.robotics
Path: brunix!cat.cis.Brown.EDU!agate!howland.reston.ans.net!vixen.cso.uiuc.edu!newsfeed.ksu.ksu.edu!moe.ksu.ksu.edu!osuunx.ucc.okstate.edu!olesun!gcouger
From: gcouger@olesun.okstate.edu (Gordon Couger)
Subject: Re: HS student seeking MOFSETs for stepper driver cir.
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Organization: Biosystems and Agricultural Engineering at Oklahoma State Univ.
References: <3272en$s9k@search01.news.aol.com> <1994Aug12.025246.11729@virginia.edu>
Date: Sat, 13 Aug 1994 02:37:52 GMT
Lines: 29

If you use IRC123 FETs you can use ttl levels put them between the motor &
ground and hook any output port and away you go. They are also available
from digi-key. The only draw back is they will on handle 1 amp at 60 volts.
You might have to opto-isolate them from the motors if you get too much noise.

Good luck
Gordon

In article <1994Aug12.025246.11729@virginia.edu>,
Gregory P. Riddick <gr3k@Virginia.EDU> wrote:
>Try the IRF511 mosfets available at radio-shack(expensive) or
>from Digit-Key(<$1.00 each).  Make sure that you drive them
>with cmos level signals (12v+) not TTL.  Using a pull-up
>resistor to 12v with a TTL level signal doesn't work very well,
>as I have found out.  Use a CMOS hex buffer if you need to
>convert ttl level signals.  You will also need a current limiting
>element in your circuit.  You can use high-wattage resistors to
>limit current, or better yet use a high frequency chopper
>circuit with an additional mosfet to limit the current before
>it gets to the stepper.  E-mail me if you would like more
>details.


                             Gordon Couger                            
                             Biosystems & Agricultural Engineering              
                             Oklahoma State University                         
                             114 Ag Hall, Stillwater, OK  74074                 
 gcouger@olesun.agen.okstate.edu 405-744-9763 day 624-2855 evenings 
    I do not speak for my employer
