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hughgilhespie

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Everything posted by hughgilhespie

  1. Hi pmlogg, I am happy to help you if I can. However, there are a few questions that need answers so that you get the best help. First off, are you actually going for a 'full' Lesvedome / ASCOM interface or just a manual solution for your dome rotation? The second question is what sort of motor will you be using to rotate the dome. The choice of motor will determine what relays are suitable. The good news is that the digital outputs from the Velleman K8055 board are buffered by a ULN2803 chip. This will handle relay drive currents up to 500 mA and voltages up to 50 volts which would be sufficient for driving almost any low voltage relay. The ULN2803 also incorporates protection diodes and the outputs can be connected directly to a relay coils. However, be aware that the power to drive the relay does not come from the Velleman board. You need to connect the Velleman 'Clamp' terminal to your own power supply. There are literally hundreds of board mounted relay modules that come with screw terminals. The choice will depend on the current rating needed for the motor. To implement the circuit you have shown, a board with 4 spdt relays would do nicely. This https://www.ebay.co.uk/itm/Mini-4-Channel-DC-12V-Volt-30A-Relay-Module-Control-Board-High-Low-U0P3/113195531357?hash=item1a5afabc5d:g:OuoAAOSw441bCEZX is a 4-channel 30 Amp relay board that is the sort of thing that would work for your application. Let us know the answers and we can offer some more focused advice. Regards, Hugh
  2. Hi @Carbon Brush, I think you have the decimal point in the wrong place. Linear expansion coefficient is 13 ppm per degree C. 10 degrees change gives 130 ppm expansion 1000 mm focal length is 1 million microns So, 10 degrees expansion is 130 microns = 130/1000 = 0.13 mm. Just for interest, using my 530 mm focal length Tak, I need to refocus every 0.5 degrees change to keep the focus in the critical zone. So, most of the focus change with temperature is something other than the thermal expansion of the metal. HTH Regards, Hugh
  3. Come on Steve, admit it! You photoshopped it!! ? Regards, Hugh
  4. Zenith sky brightness information Coordinates SQM 21.73 mag./arc sec2 Brightness 0.220 mcd/m2 Artif. bright. 49.1 μcd/m2 Ratio 0.287 Bortle class 3 Elevation 154 meters Not too bad in North Devon! As well as the Sky Quality I have also done a quick check on the Sky Quantity and as far as I can tell it goes all the way around the house and all the way up too. Happy New Year to all Regards, Hugh
  5. Hi Dave, Try https://www.leespring.com/uk_index.asp Good range and order online. I have used them quite a bit. Regards, Hugh
  6. 'So, now i've got my CNC kicked into shape, it's time to start my 14" dob build. I've had the optics since i was 21... i'm now 52 HAHA so yeah...' I am so relieved - it's not just me then. I've been sitting on a 12.5 inch conical mount mirror from R F Royce and a matching carbon fibre tube for the past 5 years. OK, it's not quite so extreme but I still feel the guilt. My mirror cell is also about 80% complete. One day............. Regards, Hugh
  7. Good point! Skywatcher mounts are also a bit picky about input voltage. I run my set up with a nominal 14 volt supply that becomes about 13.2 - 13.6 volts at the Pegasus hub I use. However, when I was looking at choice of mini computer to mount on the OTA, quite a lot of the options specified 19 volts - this is a sort of standard for laptops. When I queried the manufacturers, none of the ones I asked said that their machines would work on 12 - 14 volts. So, choose carefully and check, check and check again! Regards, Hugh
  8. Hi Steve, Another late entry to this thread. You don't say what sort of mini-pc you will be using or how it will be attached to the imaging set-up However, I can strongly recommend that you get a 12 volt powered mini-pc that you can attach directly onto your telescope. Also, while your attaching things, consider adding a USB/Power hub - think Pegasus or Hi-Tech Astro. That way you can have almost all your cables actually on the OTA. The only dangling cables would be your network cable and a DC power cable to the hub. Regards, Hugh
  9. Hi, Really good write up - thanks! I had a similar experience with my Pegasus UPB in that when I connected it to my mount computer, the computer wouldn't accept other USB inputs. At that time I was using an old EQDir cable with the Prolific chipset. I replaced this with a new FTDI based adaptor and as far as I can tell everything now works as it should. However, I do use the Pegasus USB hub in preference to the mount computer so my EQDir does come from the Pegasus hub. As everything seems to work, I haven't really done any more testing so this is far from definitive but I suspect the problem was more to do with the old EQDir cable rather than the Pegasus. HTH Regards, Hugh
  10. Or in my case, to move a little piston up and down......................
  11. OK, Windows sucks! Now then, lets have a go at Linux. Let's see I think I'll try..................... Elementary OS, Linux Mint, Arch Linux, Ubuntu, Tails, CentOS 7, Ubuntu Studio, Open SUSE, Fedora, Bodhi Linux, Mageia, Kubuntu, Mandriva, Deepin, Budgie, Ubuntu Mate, Sabayon Linux, Crunch Bang Linux, BackBox, SolydXK, NixOS, KaOS, Pinguy OS, Peppermint Linus OS, Ubuntu Kylin, AV Linux, Scientific Linux, Alpine Linux, aptosid, Russian Fedora Remix, Kantofix, Lunar Linux, Void Linux, Grml, Caldera Open Linux, Parsix, TurnKey Linux, LliureX, Yggdrasil Linux, VyOS, Debian Pure Blend I got bored at this point. Is it really any wonder that even people that would like to try Linux give up!
  12. There are some really good books on learning to use a lathe. Genuine guides for beginners that get you started. I taught myself in my sixties - at least to a level that gave me enough skills for my own needs. I have never seen any books that could do that with Linux. Regards, Hugh
  13. Hi Matthew, Just a note of caution here. Using RCA connectors soldered to Vero board is NOT a good idea. It takes a fair amount of force to insert and remove the RCA plugs and all that force is being held by some very thin copper strips. Sooner rather than later the connector will come adrift from the Vero. It is a really good idea to use chassis mounting connectors and let the box or whatever take the strain. I know that there is an enormous amount of equipment sold that have the connectors soldered directly to the pcb, I have some myself, but that doesn't stop it being a very bad design. If you intend to mount your circuit in any sort of a box, then for the sake of drilling a hole or two in it, you can have much improved reliability. HTH. Regards, Hugh
  14. I am so pleased to read these posts!! I am a total beginner at using SGP and I experienced exactly the same behaviour yesterday - a very uninformative error message. Naturally I assumed that this was me doing something daft. I spent hours uninstalling, reinstalling, watching Jared's you tube video, etc. And then - IT'S NOT MY FAULT!! Phew, Hugh
  15. hughgilhespie

    Pulsar Motor Drives

    These are photos of my homebrew motor drives in my Pulsar 2.2 metre observatory. The motors are controlled using the Lesvedome ASCOM driver software. I used stepper motors but most people use basic geared DC motors. The shutter drive is powered by a 26 volt LiFePO4 battery. When the dome is in the parked position, the battery is automatically recharged. The dome drive motor uses power from a mains-driven14 volt 20 amp DC PSU. The shutter drive connects to the main controller via wireless, using XBee modules. The main controller has a safety system built in that performs start-up checks for the dome and shutter latches and shutter battery voltage. It also connects to a Hydreon rain sensor and a cloud gauge and will close the shutter if unsafe conditions are detected. I am happy to try and answer any questions if anyone would like more information.
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