Barn door mount

[Phil]

Hi everyone i any going to make a barn door mount. Does anyone have any suggestions on a stepper motor and control unit for this. Trying to make it as cheap as possible.
Phil

[pmrid (Peter)]

Hi Phil,
on the assumption that you mean Barn (as in 'the horse has bolted') door camera mount, have a look at the link:
http://rao.150m.com/barndoor.html
Peter

[dannat (Daniel)]

I would also be interested in an aussie source for stepper motor for barn door

[leon]

Hi Phil many Moons ago I made a tracking device on the theory of a curved bolt arrangement, I have actually made two,over the years however this last one is the SS Model with vast improvements, maybe this sort of thing may suit you.

It is pretty simple to build, and works on a I rev/per minute motor with a small gear that rotates along a curved bolt of the correct size, and with the correct threads/pitch to the inch.

The curved bolt is than placed at the right distance to the center of the polar shaft, anyway I have the formula to construct this if you would like to have a go.

The formula is....R = 1,436.5 x (n/2<t), where this little think < is supposed to mean pie. in the mathamatical term, but I don't have that symbol on my keyboard.

You then just appy this formula to whatever size motor you get and thread size.

Leon

[dannat (Daniel)]

leon, where did you get the motors

[middy]

I salvaged my stepper motors from some old dot matrix printers, but I should imagine any electronics component store worth its salt would sell stepper motors. I bought my stepper motor driver kit from Jaycar electronics.

[leon]

Daniel I actually had two of them made from a electrical motor winding place, the little motors came from France, and then these guys made the gear box to bring it down to one rev per minute, however that was a very long time ago, and the place dosen't exist any more.

Leon

An just a note to Middy, these are no stepper motors, mate and although small they are that low geared you cant stop them, very powerful indeed.

[bojan]

Guys,
stepper motor can be used with 50Hz AC power, with appropriate transformer of course.
One winding should be connected to the transformer secondary directly, another one with capacitor in series (1-10uF, non-polarised type).
The rotation direction can be reversed by simply swapping the terminals of one winding .
The rotation speed can be calculated according to formula:

s(r/min) = 50/(steps*4)*60.

So, 200steps/rev stepper will rotate 3.75rev/min when powered from 50Hz.

[pmrid (Peter)]

Perhaps another suggestion: Andrews Communications advertise a small R.A. drive motor designed for EQ1 and EQ2 mounts. They are a 6 Volt drive from memory. They drive a simple worm gear in the mount via a gear on the RA motor and a second (reduction) gear on the shaft. I imagine something like this could be adapted pretty easily to run a barn door mount.
Peter

[Phil]

Thanks for the replys everyone. Leon that is one nice unit. I will ring Andrews and see what they have.
Phil

[MrB (Simon)]

Old 5.25" floppy disk drives have nice 200step/rev motors in them... if you can find an old floppy drive that is.

[Yogie-One (Paul)]

Some time ago, I constructed a digital driver for a stepper motor driven barn door tracker. It was a cheep and effective way of driving the tracker. I also built the gearbox and drive screw system for the tracker. It works well, constructed from a few components (555-timer, decade counter, power transistors, a few diodes etc) can be driven via a resistance substitution box to achieve a multitude of different drive speeds.

If anyone is interested, I could post a copy of the plans and circuit board used with a few hints and suggestions for construction.

[dannat (Daniel)]

Yogie, I wouldn't mind if you posted - or else you could send me a pm
thanks daniel

[Yogie-One (Paul)]

Dannat,

I have a few things to attend to over the next few days, but by the weekend I will post information on the driver. Please bear with me.