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Remote OTA Cover (open/close)


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Hi everybody.

My obsy is (for now) running like charm, and remote & unattended imaging is a luxury i never forget to appreciate.

I'd like to do smth good to my OTA's and give them protection of dust when not imaging, as 99% of the time the obsy is not running and OTA lenses are collecting dust, that is just unnecessary - as i'm sure i can come up with some automatic lense cover.  (I could just make a custom park position for my scope where its pointing down, but somehow this is just too easy, so i'd like to see if there are other options)

Requirements:

- Easy to build
- General parts available everywhere
- Reliable
- If DIY then pure Hardware & Electricity, no Software
- Powered by 12V

I have searched for products ready to use, but didn't find anything (except products where Flat-EL-Panel is included, and i don't need that). Maybe i missed a simple product that already exists? If yes i'm happy to hear about it.

Concerning DIY, i have thought about this, and there are multiple ways of doing this, for example when power is on, a servo pushes the lense cover up, and there is a spring attached, so when power is down, the spring pulls the cover back (whereby my problem is that the spring has to be strong enough to move the servo motor, but the servo motor has to be strong enough to resist the spring).
Also an option using gravity is a possibility.

I would really appreciate any kind of hints, i'm sure somebody has already gone through a few prototypes and has experience to share?

Kind regards, Graem

 

Edited by graemlourens
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Hi Everybody.

Not sure how to judge the slience. Rather that obsy owners do not require it as they deem it not necessary or nobody has experience making/buying such a device? 

Would be interesting to know.

Thx for Feedback, Kind regards, Graem

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I built a prototype of this for a 6" telescope and I chose to use a servo on the basis that I could turn off the motor and expect it to stay where it was. 

When closed , the lid is illuminated internally using leds to provide flat field illumination. The mechanism is built and tested, the electronics coded but not tested. There are examples also on some of the yahoo groups.

I think they are absolutely necessary for a fully remote obbo. 

I may pm to discuss how your obbo is getting on ..

Cheers

Mike

 

 

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Hi Mike.

Thx a lot for your answer, i'd like to hear more about how your device works. If you say that turning off electricity leaves servo and device in its place, whats the mechanics / software on how to close it?

If you prefer to PM me also no problem, would love to hear your approach to this device. I'd like to get as many different options evaluated before starting my own.

Kind regards, Graem

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  • 1 month later...

Sorry about the delay. Lost sight of this message.

I m using a servo unit with a small gear pinion driving a lid with a large gear pinion. The lid is semi counter balanced but missing end of range limit switches.

The intent is to provide a shuttering capability and a flat fielding capability, which means that the illumination is a telescope diameter from the lid for the flattest illumination field.

With servos the activity is under your control. For example, when they are powered on with no signal, they will be mid position. When driven they will go where you send them. In this case, to pop open the lid. Power is continually applied to keeo it open OR the whole thing is turned off and motor inertia holds it there. That means being careful when turning the power back on to prevent it closing accidentally. Or choosing a small gear stepper and again relying on motor inertia to hold it there.

The other option to consider is piezo thrusters, a stepper driven linear thruster or a small motor driven worm wheel for maximum inertia.

Any help ?

Mike

 

 

 

 

 

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maybe fashion something using the motor from an electric window off a car,that way the motor stops/starts when you press the switch

scrapyards are everywhere in the world so no shortage,its just how you would design and implement it

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Hey guys.

I nearly missed your msg, somehow i did not get the usual notification about a reply beeing posted.

I the meanwhile a friend of mine has come up with a rather simple but genious solution. We have a small servo, with appropriate electronic control parts and a capacitor that will keep charge after power is off, just enough to power the servo to go back to initial position.

So power on, servo turns (lid opens), turning power off, the capacitor has enough charge to turn the servo to its closed position.
Currently i'm testing it to see how reliable it works (i don't want to have a clear night, and have to drive to the obsy just to open a cover that is over the scope :) )

I can then post a vid/pic when its complete if anybody is interested. All the parts (excluding work, was around 20 pounds.

Kind regards, Graem

Edited by graemlourens
found out the missing word i was looking for.
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