2 replies to this topic

[David Dakstar]

I have recently acquired a Bausch and Lomb Criterion 4000 SCT. I have posted in the Classics forum about this. However, i will post here about possible D.I.Y. modifications to the telescope.

 

I do not have a power lead for the telescope and the seller did not know if the motor works. I am in the UK. On the underside of the telescope is written 110 Vac 60 Hz. On the motor it says 110V 60Hz and 3W also .75

 

From the replies on the Classic forum I have understood what I could buy to get the correct AC power supplied to the telescope. However, where I live I can only see about a quarter of the sky from my terrace. I would therefore like to travel with the telescope. and be able to use a battery to power it. Also, the telescope is very old and I do not know if the wiring is safe to use.

I could get an inverter, however these are not that cheap and I have read that they do not always work that well.

I wondered if it would be possible to convert the telescope to use stepper motors, possibly with Onstep.? The current motor is a clock drive motor. Somewhere i have a Raspberry Pi and Arduino that I have never used. I also have some small motors packed away that are probably stepper motors, I will dig them out.

I have ordered some imperial Hex/Allen keys whcih I can hopefully use to take apart the telescope so I can see the gears that it uses.

I attach some picures of the telescope.

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[David Dakstar]

I may well just change the motor for a UK one that will run correctly on the UK electric supply and use an inverter to power the mount from a battery if I take it away from home.

 

However, as I may already have some of the things I need to change to stepper motors I am curious if this is possible

 

I have in any case joined the Onstep group. It looks like a steep learning curve.

However, there was just one post about this telescope, which gave some usefull information. This said that 'The main gear is a 217 tooth 48P gear being driven by a 13 tooth gear attached to a .75 RPH motor.'

Having looked at the inside of the mount I think that this is correct. If anyone can figure out from this what stepper motor and gearbox would be needed to enable the telescope to track the stars and planets I would be grateful.

The reply to the above post on the Onstep site suggested a 50:1 gearbox.

There is a spreadsheet on the Onstep site, but it is over my head.

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[LU1AR]

My ETX 90 telescope, mounted on the base of a B&L Criterion 4000 is the best of both worlds.
The motor (which was for the Northern Hemisphere and was broken, I replaced it with a stepper motor.
The controller is a pulse circuit hand made.
Unfortunately, the reduction that I did is low and at many magnifications (More than 100) the jumps are noticeable.
I hope to find a more suitable mechanism that fits in the box below.
Edgardo

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