I have a telescope mount that has one axis which is turned by a 6V motor in order to exactly cancel out the motion of the Earth’s rotation. It is not quite exact due to a mechanical error called periodic error which causes the motion to run through a cycle of slightly too fast to slightly too slow over an exact period of 5 minutes (this is not the motor changing speed, but the worm wheel speeding up and slowing down on the worm gear). Between the 6V power supply and the motor is a controller box that allows the direction to be reversed, fast forward or rewind or pause. This is all the info I know about the system for a bit of background. I really know nothing about electronics but I talked to an electrician working at home today and he thought Arduino might do it. What finally I want to achieve is a motor speed controller which can vary the speed from slower to faster over an exact time period (5 minutes) and back to faster again and continue to cycle like this to as close as possible, cancel out the mechanical speeding and slowing. I would like to know if this would be possible with Arduino and if someone could hand hold me a bit with constructing a little electronics do do it? Greatly appreciate your help. thanks
The electronics should be fairly easy. you will need to determine what type of stepper motor you are dealing with.
There are plenty of tutorials regarding Arduino and stepper motors online.
Have a look at the link. I would probably buy a similar (but cheaper) stepper motor to set up a testing rig.
Once you feel comfortable then hook up the scope’s motor and get your timing worked out.
Good let us know how you get on.
Cheers
Sean
Thanks Sean, I know it is a 6V bipolar stepper and I think the motor controller must have a H-bridge. Please don’t confuse my use of these terms with actual knowledge!
cheers
Michael
H-bridge is correct. You actually need 2 of them to run a bipolar stepper. Get yourself a motor driver shield like this. (It will provide all the circuit protection you to protect your arduino)
and a bipolar stepper (doesn’t have to be 6v but it would make implementation easier later). I often use these modules as they are cheap and it doesn’t matter when i turn one to smoke.
Basically have a play with equipment that is not critical until you stop blowing things up. You shouldn’t blow anything up if you are careful but chances are you will.
Let me know when you get into trouble for stinking the house out.
While you are buying things, get some spare Arduino’s. The generic ones are fine but make sure it is has 5v logic ( the ones that are 3.3v will state that. If you kill an Arduino, don’t through it out. If it is a DIP chip you may just need to replace the chip.
Sorry I’ve been waffling. Currently sitting waiting for my doctors appointment.
Good luck
Sean
Thanks Sean, I just have to work up the courage to dive in to electronics, I have no aptitude for it and a habit of blowing things up since childhood. When you say Arduino’s, does this mean the boards UNO and Leonardo, there seems to be so many types.
cheers
Michael
Hi Michael
Did you get any further with your problem.
I was once told that electronics runs on smoke. You can do just about anything to it but if the smoke comes out it is stuffed. 
I never did Sean, life got in the way unfortunately
cheers
M