Newsgroups: comp.robotics
Path: brunix!cat.cis.Brown.EDU!agate!howland.reston.ans.net!gatech!newsfeed.pitt.edu!uunet!hearst.acc.Virginia.EDU!maxwell!gr3k
From: gr3k@Virginia.EDU (Gregory P. Riddick)
Subject: Re: HS student seeking MOFSETs for stepper driver cir.
Message-ID: <1994Aug12.025246.11729@Virginia.EDU>
Organization: University of Virginia
References: <3272en$s9k@search01.news.aol.com>
Date: Fri, 12 Aug 1994 02:52:46 GMT
Lines: 11

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.
