Re: (ATM) Cheap Clock Drive

[Klaus Peter Schroder <schroder@ast.cam.ac.uk>]

On 28 Sep 1995, L W Phillips wrote:

> Some months ago there was a discussion here about using the dial on a kitchen
> timer to drive a scope's polar axis. Another idea occurs to me: directly
> drive the polar axis using one of those timers used to turn lights on and
> off at preset times. The model I have has a synchronous motor and is geared to
> rotate the dial once in 24 hours. The dial pulls off, so the shaft could then
> be connected to the polar axis.
> 
> A rough test indicates that at least 30 oz-in of torque is available
> from the shaft of the one I have.
> 
> I admit I have not tried this (don't have a suitable scope).

Hey, that will certainly make a good camera-drive for (unguided) short
exposures (great if you go by airplane, with very few luggage, to a 
remote dark site), for, say 3-10 min, depending on the alignement. BTW,
there must of course be electrical current available out there, of the 
same voltage and frequency as you've got at home.......

There is/was a mechanical mashine for just this purpose ("Purus")
on the german market (there were add's in S&T as well), a good buisiness
during the Halley-hype.

However, I would NOT put my telescope on an axis that ends in such a
drive! There will certainly be a lot of bending in alpha...... I suppose,
the tiny gear (by atm-standards) cannot cope with the temporary loads 
coming in from wind and other sources without either bending or even damage.

Cheers, Klaus-Peter