Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.


  • Content Count

  • Joined

  • Last visited

Community Reputation

41 Excellent

About pmlogg

  • Rank
    Star Forming
  1. When I planned the electrics for my dome 11 years ago I decided, as a precaution, to house all double sockets in IP66 boxes and similarly for dimmer switches, timer socket for the dehumidifier, fixed power supplies for the mount, my main imager and other ac to dc adapters. I boxed in the pier with plywood, with a gap to prevent vibrations. That produced four wooden surfaces to screw components to. The cabling from the house all comes to the pier initially but then power, usb and networking cables all go under the decking floor to a desk area. I didn't want to alter the dome itself so I sandwiched one of the section joints with uprights and screwed plywood to that. White and Red lights, a 12V supply and more power points are attached to that, located under the fixed desk. One decking board is double hinged so that it can be lifted up, crane like, to access the cables. I've had no shortage of electric points. Now I have a monitor on an arm fixed to more wood, this time sandwiching the joint above the desk. It can rotate the monitor flat against the dome wall or move it out for convenience. The lamp shown in the picture is now mounted on that wood. The computer is in the house, under the stairs, with another screen , keyboard and mouse - that's the 'warm room'. The only thing I would have done differently would have been to have a larger diameter pipe for pulling more cables though e.g. usb3. I do have a wire to pull more through but not sure it wouldn't snag. The dome rotation is powered now but by 12V battery. After use it is recharged from the mains, although there is an external solar panel for recharging too.
  2. My understanding was that there were vibrational advantages to having a heavier weight closer than a lighter weight further out.
  3. I also enquired SBig recently about a camera issue. Initially they just said to send it back. When I told him that it was from the UK he gave me some things to check, including the external power supply and the usb cable. Running a short cable and from the 12V supply rather than the 240V one it seemed to be operating the shtter fine (his initial diagnosis). I've been waiting for a clear night to test further before deciding whether it needs to go to California. I would agree with using a courier to send the camera for a US repair. The Post Office did not have a clue and had none of the correct paperwork. UPS (I think it was) or DHL was spot on. I did get charged VAT on the repair cost - which involved new parts but that is what is supposed to happen.
  4. I find that sometimes my plastic pipe, which is much longer than yours, becomes flattened. That's how it looks when I have to empty the tank. I squeeze it back into shape and then it's fine for some time before having to do it again.
  5. I forgot to include the diagram of the pier base from that article. Here it is.
  6. Here are three photos and the diagram of the underfloor supports. You can just make out the hinge close to the pier in one of the interior images and the cut for the other hinge (hidden below the floor) in the other image further along the same board, just at the bottom of the frame. When I looked back at my notes I see that after cutting the flooring boards to length I laid them out on our patio and used a long piece of string secured in the centre and marked out the curved cuts at the outer edges of the boards. For the cabling the power is an armoured cable; the electronics through drain pipe. The cabling runs from the house (my warm room is under the stairs) to the pier under the 3m stone circle and then from there under the floor to the desk area.
  7. Sorry for the delay in replying but been under the weather for a couple of days. My pier is metal, made by a local welder from pipe then powder coated. The pier support is poured concrete using measurements from a Sky-at-Night article on DIY domes. Not being very good at just doing carpentry on the hoof I used a spreadsheet to work out the decking panel lengths and "2x4" supporting framework and I did a diagram with the parts numbered. My dome is the 2.7m version so the measurements will be different. I did the wood cutting and preparation during a good spell of weather in the late spring, before the dome arrived. I used end-grain preservative on all of the end-cuts as well as the screw and cabling holes and used normal decking preservative for the flooring. I numbered the support sections as per my diagram, having it in mind that it might someday have to be re-assembled elsewhere. Once the dome arrived and was put together I assembled the floor inside, using screws. I did have to make some adjustments, including slots to accommodate the flanges between each of the four dome wall sections, and a bit at the door - but overall I was pleased by the fit. The cable access decking board has a hinge at the pier end and another in the middle. It's well supported by the sub-structure so is as stable as the rest of the floor. The pier is boxed in, for fitment of power boxes etc., with weather-proofed plywood but with access holes for cabling. It doesn't touch the pier, to avoid vibration. I made a hexagonal plywood table top which goes around the pier at the top, on which I can rest bits and pieces - the only problem I did have later was potential contact at high elevations (I'd bought a longer telescope). So I extended the pier by 30cm. The 'desk' top at the pier wall was a thing I bought to use when sitting on a couch with a laptop, painted black. I sandwiched the wall flange nearest the door with vertical 2x4 and then attached plywood to it for more cabling/power boxes and lights (one red, one white). I used scraps from the decking panels as supports for the desktop itself. Originally I used a small self-standing screen which sat on the desk but that's been replaced by a larger screen on a hinged wall mount, attached to more wood sandwiching that same flange but above the desk. A desk light attaches to that too. Again I did an excessive number of drawings too plan out the pier surround and desk but both have worked without need for modification. The only down side with the floor is that there is a potential to lose small items between the floor boards (I left narrow gaps for ventilation). Having learned that lesson I have a thin rubber-bottomed floor matt that I can put underneath when working with anything small enough to be lost. I have images on my home computer. I will find them this evening.
  8. Concerning bases and decking, I bolted mine down onto a sandstone circle just a few inches bigger in diameter than the dome. It was laid after a central cube of concrete was poured for the pier attachment and the cabling trench completed. I just left out the central circular stone. The theory was that if we move I 'just' need to cut the bolts for the pier, remove or seal up the wiring and install the circular stone - to produce a circular patio. I have decking but inside the dome, producing a floor raised above any ingress of water and allowing cables to be laid under a hinged decking board. The cables connect a desk at the wall with cables that come into the dome at the centre, by the pier. After quite a few years the internal decking has only needed to be brushed off. I like it as it feels much warmer than concrete and I suspect warmer than rubber tiles too.
  9. The current version Pulsar 2.7m appears to have a 700mm shutter. The original version was wider at 780mm. I've not tried side-by-side; I have one piggy-backed on the other, but the total height of the pair is less than your biggest scope. Of course when your scope pair is on one side or other of the mount the two scopes would no longer be side by side, but at the extreme would be above each other, reducing the effective width.
  10. For Canon cameras that do not have wifi but do have a usb socket, e.g. the 450D, VirtualHere could be an inexpensive solution. I am using it for observatory control with a PC and if using the software to provide a single wifi usb link it is free, the $49 cost is if using it for multiple usb connections. You do need hardware to act as a one-port wireless wifi router and power for it. VirtualHere recommended the GL-MT300Nv2, available recently on Amazon for £17, which works fine for me. Add a powerbank to provide usb power out and that's it. The people at VirtualHere in Australia were very helpful, even though it was the free version I am using. However the one downside is that the wireless router forms a one-to-one link with your computer so no concurrent wireless e.g. internet connection. Peter
  11. Hi Peter I've been reading the thread on automating the dome and see you mention a 2 part shutter. How are you going on with automating that ? I have a similar dome and working on the shutter.  You also mention other sensor integration, how are you planning that , if you don't mind me asking ?



    1. pmlogg



      I'm not actually doing anything about the shutter at the moment.  There is an Irish amateur astronomer who has a first model Pulsar 2.7m dome like mine.  He started from scratch and used Exploradome parts that he bought in the US and brought back to Ireland. 

      Unlike me, and more conventionally, he has the Velleman card mounted on the wall of the dome so did not need a wireless, battery operated, system for rotation.  This is a link that shows something about it.  https://www.irishastronomy.org/kunena?view=topic&catid=22&id=95329#96208 

      Exploradome have changed their system for the lower shutter to one that uses a pair of electro-hydraulic rams.  I did not have much joy getting a price from them but it does appear that they can still supply, on request, the old-style lower shutter part.  They use very expensive (but apparently very good) motors,  the cost now even higher with the very weak £. 

      It does not look impossible though to have someone skilled to replicate the actual metal hardware.  For the upper shutter you will see that Michael used parts from Exploradome's rotation system.  The acorn gear and trackway are available separately from other US sellers and are not very expensive.  On how it all works and how he did it Michael is very approachable. 

      Michael has however told me that he really doesn't use the automation of his shutter. The main reason is that he finds the weather where he is too unpredictable to rely on it closing quickly enough, even with a weather station.  As our weather in Scotland is probably no better my thinking was that spending a lot of time and money on the shutter, and then not using the automation would be a waste.  To me the manual system is easy and likely quicker than any sensible motor system.  Rotation is of course different, not having to go out to nudge the dome around during an imaging session is much more useful and I think being able to slew to new targets from indoors will be too.  I don't though have a method to automate flats which remains one of the limitations to my automation.

      Before Michael told me that about the shutter I spent quite a while looking at the option of using rams for the lower section of it.  I could not find a position for the bottom of the rams that did not involve having a pretty massive framework projecting into the dome.  I didn't try to take advice on that but there are a lot of bright people on this forum so one of them might have the expertise to advise on that sort of solution.

      Sorry not to have an actual solution for you.



  12. Many thanks for those good wishes. I have been keeping an eye on shutter plan. The 2-part shutter on my dome does complicate matters, requiring another motor and extra limit switches. My thinking has been that having my VM110 already moving with the dome, and being linked by wifi to the controlling computer, should make hard wiring to the VM110 possible. Perversely linking the cloud and rain sensors would be made harder. Thanks Peter
  13. Hugh and Alan Finally some clear sky tonight so I was able to give it a good test, not imaging but just slewing onto different targets. I had to increase the GEM offset figure in POTH to get closer to the mid-point of the shutter but other than that the slaving seems to be working exactly as required. It's such an improvement from having to hold down the button on the key fob while the dome slewed to a new target. Also positive is that the VM110 and GL-MT300Nv2 seem to draw very little power so that the power bank re-charges very quickly. On current performance I don't think that having those components powered by a battery is going to be an issue. A cold winter night's imaging will be a better test though. The Wifi link has been glitch-free too. Thanks Peter
  14. Alan Thanks for that, and again for your help. The pillow bearing is at an angle as I slightly mis-calculated when drilling the hole for the shaft through the casing. The Igus pillow bearing insert is a ball so the angle I've mounted it at makes no difference to its operation. It's there to support the encoder wheel shaft rather than exposing the encoder itself to radial forces. The two shaft bearings are also from Igus and of similar format, i.e. balls within a housing. The speeds of rotation are well within the tolerances of the bearings which do not need lubrication and won't rust. If I'd not managed to get the alignment sorted I had thought to add a second pillow bearing in that space but it would have required moving the encoder bracket backwards - and space is limited for that, or start again with a new enclosure but that would have been a lot of extra work. Luckily using the adjustment that was there with more care than the first time round did the trick as far as smooth rotation was required. I should have done more from the start to restrict axial motion of the encoder wheel shaft as I did wonder about it earlier in the process. It looks a bit Heath Robinson with the attached brackets for the Hall Effect Switch and the 2nd shaft bearing but it seems to work. In terms of cosmetic appearance I'm happier with the enclosure box for the relays and VM110. The three cable entry points have worked out pretty well. I think there is probably enough room in the enclosure for more relays if I do, in the future, want to try shutter automation. However, with the need for things to be switched on, uncovered etc. and my fear of depending on the system reacting quickly enough to close in the case of rain a powered, automated shutter is a low priority. My next stage will be to verify that the data I put into Lesvedome in respect of the mount geometry is accurate enough to maintain alignment shutter to telescope. Thanks Peter
  15. The Hall Sensor, tested with a spare magnet, registered under the K8055 programme so the encoder box was refitted, Lesvedome run and it works with the resetting to the Home Setting taking place when the Hall Effect Switch rotates past the fixed magnet. There was no time tonight to check a slaved slew nor that the other parameters I entered into Lesvedome are accurate enough for consistent alignment. That for another night. Here are pictures of the revised encoder enclosure internals and externals. I used a longer shaft which goes through the new external bracket. The space for the wheel is such that the shaft bearings above and below act as a proxy set screw, removing all but a fraction of a mm up and down motion. Also shown is the complete system other than the original Pulsar/Rigel keyfob and receiver that form the 'manual' system. The switches on top of the original Pulsar/Rigel unit are 3-way. Pushing outwards to the dome connects the new system to the battery and rotation motor. The middle position is off and the inwards positions connect the original Rigel circuit board etc. The wall mounted box contains the Velleman VM110, the relay board, UBEC 12V to 5V regulator and the connections DB9, USB and XLR for 12V from the battery and to the rotation motor. On top of the Pulsar/Rigel unit is the Powerbank and the GL.iNet GL-MT300N-V2 Mini Router. They are brought indoors for charging. Protruding from the bottom right of the Pulsar/Rigel unit is the Encoder enclosure with tensioning spring, and DB9 connecting cable. Just to the left of it, on the dome wall is the fixed magnet. It remains to be seen if the wifi link can run without dropouts but so far the signs are promising.
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.