A quick potted history is probably due.

The scope is a Fullerscope MKIV mount with a 12" newt on it. I bought it about 11 years ago knowing it need pulling apart and rebuilding, but the price was low, the mount solid and the optics were good.. The bits that were rubbish I could change.

The Newt has now been modified with a window so I no longer have diffraction spikes and tube currents are better suppressed. It does however make it rather heavy... I can just about lift it, portable is not the word.

The mount was refurbished with the paint being stripped off and was then powder coated in white. It has a drive system under development which has to date been through 3 itterations.

The whole project was started before I took my break from astronomy and so by the time I came back to the hobby a few months ago was mostly obscelete. It was a stepper motor system driven off a PC.. not the excellent Mel Bartels system, but one of my own as I like to challenge myself to new things. These days you don't need a PC, a PIC will do the thinking quite adequately and is easy to programme. The driver chips available now also mean microstepping is a doddle.

As it stands the Drive is silky smooth despite the stepper motor direct driving the worm. The 150x microstepping is quite sufficient to stop vibrations, and the lack of a gearbox means I have fewer errors to correct. (driver chip : allegro A3972)

What I now need to do is change the PIC I'm using. A 16F690 is fine for basic timing but no use for anything involving "sin x", tried it and a 32 bit "sin" takes over half the memory for that one instruction. So will be migrating to a dsPIC... but not until I've got the rest of the system good enough to warrant it.

Which means my home brew hand controller also needs to do the business... at the moment it's not mechanically up to it. So I need some boxes around the electronics otherwise they get wet and stop working.

Hopefully this Blog will trace the continued development of the hardware and software.

Derek