Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Safety switch for home position

  • Please log in to reply
9 replies to this topic

#1 Chippy10

Chippy10

    Lift Off

  • -----
  • topic starter
  • Posts: 18
  • Joined: 10 Sep 2016

Posted 30 August 2021 - 06:46 AM

Hi

I have a motorised roof and was thinking of adding a safety switch to the mount (Az-Eq6) which sits on a pier, as the telescope needs to slew about 90’ horizontal before roof closes. So far I’m thinking of a snap safety limit switch attached to pier some way. Wondering has anyone come up with novel design/ pic’s ?

#2 Phil Sherman

Phil Sherman

    Soyuz

  • *****
  • Posts: 3,513
  • Joined: 07 Dec 2010
  • Loc: Cleveland, Ohio

Posted 03 September 2021 - 08:09 PM

That's difficult to do with that mount because there's not a good location to easily mount the two switches you need and not have them interfere with the movement of the mount. My solution was to mount a small mirror on one of the spider vane adjusting screws and use it as a reflector target for a cat toy laser. The reflected beam goes into a photocell detector which indicates that the scope is parked horizontal and alongside of the pier. DEC errors move the mirror out of the beam while RA errors tip the mirror, moving the beam off of the detector.

 

My observatory partner uses a commercial unit for his scope. His reflector is a corner reflector similar to a bicycle one and his emitter/detector is a single unit that includes a mechanical relay. His park position has more slop in it than mine because the emitter beam width is much larger than a laser pointer. He also has a lot more roof clearance when his mount is parked than I do.



#3 Chippy10

Chippy10

    Lift Off

  • -----
  • topic starter
  • Posts: 18
  • Joined: 10 Sep 2016

Posted 04 September 2021 - 04:34 AM

Hi phil
After studying mount head on ax-eq6, it certainly wouldn’t be an easy task. I was thinking of an miniature rectangle inductive switch and a longer grub screw that holds the saddle. Then I was giving up on it and trust automation.
Voyager software looks interesting.
Anyway, that’s a great idea of using a reflector/ sensor.
I had thought of putting 2 looking across observatory over the home position but I was concerned about false alarms with dew?
I suppose I could make up a few dew shields.
Just curious, how did you go about automating your roof, Arduino, Rpi, …?

Padraig

Edited by Chippy10, 04 September 2021 - 04:35 AM.


#4 Phil Sherman

Phil Sherman

    Soyuz

  • *****
  • Posts: 3,513
  • Joined: 07 Dec 2010
  • Loc: Cleveland, Ohio

Posted 04 September 2021 - 10:41 AM

Hi phil
........
Just curious, how did you go about automating your roof, Arduino, Rpi, …?

Padraig

It's not a simple answer. The building is controlled by a pi that runs a customized client server program I wrote. This was necessary because I share the observatory with a partner and when both of us are using our scopes, both of us need to immediately know if the other changes anything in the building. The software I wrote automatically takes care of this. Sensor data is fed to input pins on the pi while outputs from the pi control two separate 8 unit relay boards. We're set up so both scopes should be parked to move the roof. There's an override for the park sensors to allow moving the roof if one or both of them fail. Backup for the parked sensors is a webcam pointed at the piers that easily shows that the scopes are parked.

 

The observatory is off grid and normally doesn't have any AC power available. We wired the building for AC which we can supply from a remote controlled (our modification) battery powered inverter or, if we are on site, from a gasoline powered inverter plugged into an outside socket. The battery bank is charged by around 400 watts of solar panels feeding an MPPT controller and a wind generator. The wind generator keeps the batteries charged if we have multiple cloudy days, a single season occurrence. The solar panels are wired in a series/parallel arrangement which cuts the current from the panels to the controller in half. This cuts power losses in the wires between the panels and the controller by a factor of four and slightly extends the hours when the panels can charge the batteries.

 

The roof is moved by an automotive winch motor which is DC powered. When we purchased it, it came with a mechanical hand controller and a port for a wireless plugin controller. It was easy to add external wiring to the relay coils to allow the pi to control it. The winches currently being sold no longer have the hand controller but it's still easy to install external wiring to control the relays. This motor required significant modification including some machining to use it for this purpose. We're investigating replacing it with a DC motor that has a standard sized output shaft on it.



#5 Chippy10

Chippy10

    Lift Off

  • -----
  • topic starter
  • Posts: 18
  • Joined: 10 Sep 2016

Posted 04 September 2021 - 12:17 PM

Wow Phil,
That’s some undertaking, there’s me scratching my head on how to automate ROR at the end of the garden.
I probably just take the plunge and get Arduino with relay card , then jump in the deep end and learn to code.
Electrician by trade, so hoping… small bit code , try and get it to run with Nina.
Time will tell …

#6 GrandadCast

GrandadCast

    Apollo

  • *****
  • Posts: 1,074
  • Joined: 23 Jan 2011
  • Loc: Hill Country, Texas

Posted 04 September 2021 - 04:43 PM

I am still working on my Arduino project (grandkids spent the summer with us) and started out with a reflex photoelectric switch sensor. The sensor (mounted stationary on the pier) sends out a beam that requires the special polarized reflector (mount on the mount) to line up which then bounces back to the sensor. So in park they line up. One good thing about the polarized requirement, any other light source will not cause a false state. Now, I am not a fan of turning a beam off and on during an imaging session, else having a beam shin through the observatory isn't wise, so I changed that to a simple magnetic switch. The sensor is mounted on the pier and the magnet is double tape to the mount. So far this has work fine. I can change to either beam or magnetic sensor quickly so which of the final component I will use hasn't been set yet. But with the magnet one I don't have to worry about a false trigger or turning it on/off during imaging. Either one will work and cost under $30.

 

https://www.amazon.c...e?ie=UTF8&psc=1

 

 

Jess

 



#7 Chippy10

Chippy10

    Lift Off

  • -----
  • topic starter
  • Posts: 18
  • Joined: 10 Sep 2016

Posted 04 September 2021 - 04:58 PM

Hi Jess
Never thought of the light been emitted by the sensors, a good heads up.
Cheers.

Padraig

#8 Raginar

Raginar

    Cosmos

  • *****
  • Posts: 9,821
  • Joined: 19 Oct 2010
  • Loc: Pensacola, FL

Posted 08 September 2021 - 03:46 PM

Hi

I have a motorised roof and was thinking of adding a safety switch to the mount (Az-Eq6) which sits on a pier, as the telescope needs to slew about 90’ horizontal before roof closes. So far I’m thinking of a snap safety limit switch attached to pier some way. Wondering has anyone come up with novel design/ pic’s ?

I used 12V IR sensors with reflectors.  It allowed me to keep cables away from mount/scope.

 

Chris



#9 Chippy10

Chippy10

    Lift Off

  • -----
  • topic starter
  • Posts: 18
  • Joined: 10 Sep 2016

Posted 08 September 2021 - 03:53 PM

Hi Chris
I suppose if my using uv/ir cut filter , light from the sensor shouldn’t effect imaging. Even though some people using ir camera’s in their observatory say it can effect images. Maybe their not using a filter?
  • Raginar likes this

#10 Raginar

Raginar

    Cosmos

  • *****
  • Posts: 9,821
  • Joined: 19 Oct 2010
  • Loc: Pensacola, FL

Posted 10 September 2021 - 01:50 PM

The beam isn't that wide; It's not like the flood light from a web cam or anything.  It's also low so it should be shining sideways at a mid point of your scope.  You could park the scope with it pointing straight up so the tube gives you a lower point of contact.

 

I never once noticed it influencing my images; I had 2 of them and a web cam laugh.gif

 

https://www.amazon.c...1300175&sr=8-4 

 

This is similar to what I used.  


Edited by Raginar, 10 September 2021 - 01:59 PM.



CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics