RE L293 & cheap stepper

To the person who asked about driving a 1.9v stepper with an L293.

I accidentally confused the 293 with the L297/298 combination in my
reply when I recommended using a high voltage chopper drive capability
for greater speed/torque without burning out the coils. I don't know
if the 293 supports that, but would recommend the 297/298 pair which
do when used together as an H-bridge and step/direction translator
system which includes the comparator necessary to make the chopper
circuit. You could run this off anything from around 12 volts (good
for your small motor) up into the 40 volt range, for good high-speed
performance with larger steppers. When properly configured the
chopper limits the current to a safe level, so the excess voltage just
permits higher switching speed - kind of like having a big engine in
your car in order to accelerate onto the freeway, rather than to break
the speed limit.

If you do a web search on the combination of these part numbers, you
will probably find an online description of the same project writeup
that I worked from in building mine (from a robotics group in either
Seattle or Dallas) The MFR's datasheets may also show how to
interconnect them.

The step/direction method is slightly easier to program for and is
compatible with most of the hobbyist type software port. Buying both
chips will cost a few bucks more, but save time and money over
trying to hack together your own chopper circuit.

Chris


--
Christopher C. Stratton, stratton@...
Engineer, Instrument Maker & Horn Player
(978)538-5179 work, (617)492-3358 home
30 Griswold Street Cambridge, MA 02138
http://www.mdc.net/~stratton