Auto-guiding an old mount

For getting reasonable images with a longer exposure than a minute it soon becomes obvious that some form of auto-guiding is highly desirable. As my mount is a home built effort which is now over 20 years old it uses analogue motors and a variable frequency oscillator. Most current auto-guiding electronics and software seems optimized for the many modern mounts currently available so I wasn't sure that a system could be made to work on my aged mount. Some discussion with an electronics savvy friend encouraged me to try and with his help a working system was eventually achieved using the SPC 900NC webcam & PHD guiding software. Though not perfect it does seem to work surprisingly well. When the telescope is suitably balanced it stays locked on though there is sometimes a slight ovality to star images on the RA axis that comes and goes. I've yet to pin down the cause. (click on image for larger view)

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