The resistors R18 and R22 that should have been connected to pin 8 of U4 were mistakenly connected to pin 9. The present versions have been corrected. A minor error on the component layout is that there are two versions of C2, in the upper right and lower left corners - let one of them read C11 instead (they are equal). This is not corrected on the image. Here is the latest schematic by David H Bevel - I have
Stepper - schematic

updated the text with his parts numbering (I hope, but I may have missed occasionally!). This schematic, the parts list and the PCB pattern (Full scale at 500 dpi - or a 1:4 version for viewing ) (note that the pattern is seen from the component, NOT the copper side!) and an alternate PCB pattern with less copper etched away, as well as the component layout and the timing diagram are mutually consistent - I am sure. Also, here is a diagram of the connections and a picture of Dave`s version built and ready - Thanks a lot Dave for all the work you`ve done ! Folks, please respect our copyrights. Next in the pipeline - the modification necessary to use a low-voltage stepper motor using 3V supply (and 12v for the control circuit). If this is of interest to you, mail me at nilsolof. carlin@telia. com. This circuit was designed primarily to feed a 5. 25" floppy-disk type stepper, driving a threaded rod, but may be used with other platform designs. It features: I`ve been using an equatorial platform for my 13. 1" and 6" Dobs. I consider the platform a very useful addition - a full GoTo mount can do more, but I think the mechanical complexity is also in another league. It is of course particularly useful for planet studies - not least if you like to show planets to friends and acquaintances, as you do not need to re-position the telescope every minute! However, the full-step circuit I have been using (until I made the circuit...

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