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Found 62 results

  1. Hello, It's been a long time since I've posted in this forum, anyway I've picked up a Skywatcher 200p F/6 dobsonian as a DIY project whilst I continue to work on a new telescope from scratch, (I've started to grind the mirror). I'll be making improvements to this dobsonian as a project and learning experience, I've already got a temperature controlled fan which has a probe that can measure both mirror and ambient temperature. I'll be measuring the primary mirror with my in progress Foucault/Ronchi/Bath Tester when that's finished in the next couple of weeks, may even refigure it depending on results. But I'm most excited about this right now. The blackest Black Paint as an alternative (hopefully better alternative) to flocking! This stuff is seriously black and flat, I backed it on kickstarter and received 3 bottles along with goodies. I plan on painting the area opposite the focuser, area around the primary mirror, inside the focuser drawtube, potentially the secondary mirror holder and edge of the secondary also. It's a shame I don't have any flocking to compare it with but it looks incredible. This video shows just how impressive it is (moreso than my little tester I've done). https://www.youtube.com/watch?v=uJIIzcbRD9w I'll try and get some decent before and after pics. Dan
  2. Ardufocus is a full open source Moonlite compatible focuser. The source is still under heavy development so things move around a bit. To access source code and detailed instructions visit the Github repository, for the 3D objects visit Thing #2446069. Motivation After buying the CCD, filter wheel and filters I was broke but still wanted to have an automatic focuser. Design Goals Moonlite compatible: This was a very important part of the design as I didn't want to spend time and effort dealing with ASCOM and INDI drivers, the Moonlite focuser is a well known, reputable rock solid focuser. The serial protocol used by them was easily reversed engineered (plain ASCII) and most of it was already documented on the Internet. Cheap: Another big point was to made it as cheap as possible recurring to as few parts as needed. That's the reason why the 28BYJ-48 stepper motor was chosen, out-of-the-box using the ULN2003 gives you a really cheap (less than 2€) focuser for medium loads (380gcm). If you require the focuser to driver heavier loads (800gcm) then the motor itself can be modded into a Bipolar stepper motor and driven by the A4988 step stick which will cost you less than 1€. Builder friendly: Using off-the-shelf components such as the Arduino Nano and easily available parts Ardufocus is aimed to be build by anyone with a soldering iron and some patience, no degree in electronics required. Hardware It was built on top of a standard ATmega 328 Arduino such as UNO, Pro or Nano; currently it does not support the Mega or any other ARM based board. BOM 1x Arduino Nano 1x A4988 Stepper Motor Driver Module 1x Electrolytic capacitor 10uF 1x NTC 10K 5% 1x Resistor 1/4W 10K 1x DC Power connector (male, female pair) 1x DB9 connector (male, female pair) 1x 28BYJ-48 Stepper motor 3D printed parts To download and print instructions for the 3D printed parts have a look at the Thing #2446069. A4988 driver with a Bipolar motor Example schematic how to building and Ardufocus using a modded 28BYJ-48 Stepper motor.
  3. So my birthday just past so money to splash on astro stuff , i will have my 1000D modded by juan at cheapastrophotography and also have ordered an autofocuser from deepsky dad https://deepskydad.com/autofocuser i know they can be done DIY but this is a neat package and costs about the same as a SW autofocuser and a hitechastro focusmaster and i`m no electronic wizard and pavel seems to have a good product and works with ascom and confirmed it works with APT i will update in a few weeks time when hopefully i will have received and tried out .
  4. JemC

    The Obsey

    In the famous words of Bilbao Baggins, I'm going on an adventure! Almost 2 years ago i got rid of my old shed with the intention of replacing it with a R O R shed, Well a lot has happened since then, but no R O R shed ? No way i could build one, my DIY skills are rubbish. My mount and scope plus other bits have sat in the garage ever since, mainly because it's such a pain to drag everything out and set up only to be thwarted by cloud/rain, so i decided that they would stay in the garage until the arrival of R O R shed, so fast forward 2 years..... Well! while browsing some astro sites i happened across an advertisement which said something like wooden observatory for sale, 7ft x 7.5ft, buyer to dismantle and remove, so me being in need of one had a look at the pictures he posted, that will do nicely i thought, so i contacted the seller and asked for more info and pictures, It's not a roof that rolls off onto supports, it turns out 1/2 of the roof rolls over the other 1/2 with a front section of the shed that drops down, I was happy with what i received from the seller, he couldn't have been more helpful and seems a really nice bloke, Right then, where are you located mate i asked, Bovey Tracey he replied, to be honest, i had never heard of it, so time to consult google maps.. Well it turns out it's only about 270 miles one way from my house in Lancashire ? (so round trip of approx 540 miles) Time to make a decision, do the positives outweigh the negatives, is it going to be a cost effective solution in getting my R O R shed ? after doing some calculations and a little more contact with the seller, the answer to the 2 questions above is YES ? I have hired a box van for this coming Saturday,shangied my brother in law to accompany me and.. I'm going on an adventure to Bovey Tracy to dismantle it and give it a new home in sunny Lancashire, even though my DIY skills are rubbish i feel i have to give this a go, All in with the cost of The Obsey (as it is now known until i can think of something better) and with the hire van/fuel and brother in laws dinner it's going to set me back approximately £570 and a day out, I'm well chuffed with that, the cheapest quote i had to have one built was £1000 I have a couple of pictures of the obsey in it's current location if anyone would like to see them, Sorry to waffle on so long, Thanks for reading JemC
  5. For the past couple of months I've been working on a project which I named Arduheater. Arduheater is a full open source intelligent heat strip controller for astronomy usage. Source code is available at: https://github.com/jbrazio/arduheater The main design goals were: Remotely controllable This was a very important part of the design, most heat controllers, specially the DIY ones, rely on the PWM signal for each channel being manually adjusted by means of a potentiometer. This either requires the user to be near the device tweeking it or to set it to a temperature that may be higher than the one really needed thus completely trashing efficiency. Arduheater uses a serial connection so you can use any USB-Serial-TTL dongle to adjust it's settings either you're 2 or 2000 meters away. Efficient energy usage Manual adjusted heater will either require the user to be tweeking it or they will wast more energy than necessary due to the general tendency to use a higher that required setpoint, this is valid for any PWM or bang-bang style controllers. Arduheater uses a temperature sensor (DHT22) to measure basic environmental properties such as temperature and humidity, knowing them both makes the calculation of the dew point[1] possible. Arduheater also has a temperature sensor (NTC) for each heating strip, allowing the micro-controller to have a rough estimation of the temperature the equipment is at; it will be a rough estimation because we are really interested on the lenses surface temperature but we are actually measuring the heat strip temperature, to mitigate this, Arduheater allows the user to set specific offsets per heating strip. Arduheater uses a PID controller[2] to efficiently manage the energy so only the required amount of energy to maintain a temperature setpoint is delivered to the heating strip. This is possible due the usage of a PWM signal while driving the outputs; the delta between the environmental dew point (plus offset, i.e. setpoint) and the heating strip temperature will make the micro-controller output a PID-calculated PWM signal until this delta reaches zero. In practical terms if a 12V heating strip full on consumes 12W of power (1A) it may be possible for it to use only 1W or even less to keep the equipment above dewpoint and the power usage will be automatically updated during the night as conditions vary, so the system will be always using the least amount of power to keep the dew away. Builder friendly Using off-the-shelf components such as the Arduino Nano and easily available parts Arduheater is aimed to be build by anyone with a soldering iron and some patience, no degree in electronics required. Allow up to four independent heat outputs Each of the four outputs have independent controls such as offset, min and max output power and of course the three main properties of the PID controller (Kp, Ki and Kd). Here are some shots of the bench prototype using a power resistor as the heating element and it's serial configuration interface: The "field" prototype on it's box: The heating strips (more build info will be provided further ahead): And of course all of this would not be possible without the usage of the force. ;-) I hope someone may find this project useful. I'll keep this thread updated as soon as I'm able to release the source code, schematics and build instructions. [1] Dew point is that dreadful threshold at which water condensation starts to happen on the lenses/equipment. [2] A proportional–integral–derivative controller (PID controller) is a control loop feedback mechanism (controller) commonly used in industrial control systems.
  6. Hi. Finally it's time to start a project i have been planning for a while. My remote Linux - INDI observatory Some info about the project. The observatory is going to be box style. I don't do any visual stuff, so i wont make room for myself. It is going to sit on a south facing second story balcony at my parents place. It's by a fjord near Drammen, Norway, so almost everything southbound is water and zero light pollution. The house itself sits on a spot with mostly green and yellow on the LP map, so beats my apartment where there is dark red LP as far as the eye can see (sadly).. To start things off, I'm building the pillar. As it's on a balcony, there will be no way to dig and cast a base in concrete. However concrete (b30) will be used to make the pillar more substantial. I want it to be very rigid, and I guess by having some weight to it, some flex in the floor will be "pre flexed". Any project starts with a good drawing so here is some cad. The outer tube is a cardboard casting tube. It sits on a wood plate with a total thickness of about 3.6 cm, has four m20 threaded rods that will be casted in with four 50x35 cm steel angels for stability. On top there is three steel plates connecting the base to three m20 bolts with mounts for the celestron avx. I will use the celestron's plate from the tripod (removing the legs) on top to mount the head on. The gap between plate one and two from the top is to be able to adjust and level the mount. I will have to get the three plates and three blocks on the right fabricated, but hopefully at a acceptable prize, hopefully... This weekend was mostly drawing, but did get something started. Let me know what you think about the design. More to come as project progresses...
  7. Hi all, After having my mind programmed into thinking that home observatories should be round or square I saw an article showing a triangular one. This altered my thinking completely. I had some plywood and other wood left from building my house so took a couple of days to build my observatory. The size was dictated by the tripod base and the movement of the telescope on the mount. I have a NEQ6 Pro and 8inch ACF. The first thing is to align the tripod along the meridian North South with the help of the sun's shadow and the time. This means that with the scope parked it takes up less room. The roof hinges over with the help of a counterweight (not shown on my first video) and the base of the observatory is a equalateral triangle about 5-5 feet high to allow the scope to see most of the sky. This setup allows for access to the scope but is really for remote viewing. The triangular base is approx. 6 feet on each side but the roof requires room on one side to be hinged over. The observatory can be built from 4 sheets of 18mm exterior grade ply and one sheet of 5mm marine ply for the roof and 3 4.2mtr length of 50mm by 100mm treated wood. The cost could be less than £200 if you can use some reclaimed bits. The video I made is about 20 minutes long and involved me thinking and working things out while building it. The triangular construction is much easier and stronger than a square or circular one. The design means I have the scope setup and ready for those short glimpses of clear sky while also able to try remote control of the scope with the roof closed. Since the first video I have put more hinges on the joint and a beam (made from hardwood I bought as an off cut) with a couple of old rail track plates used as counterweights. The next thing is to use a garage door opener to remote the opening of the roof. So here is the link to the video. Please just see it as an example of what you can do, not as a 'this is the way to do it' video. If I was building it again it would be similar but better.
  8. Here we go. It's been a long long time I've been wanted to have my own obsy. Having recently (2y ago ) upgraded my scope to a LX200 10", I found that setting up that scope was no longer a 10 min operation and as a result, my observations got severely reduced to close to nothing. I have to admit I've taken on a full house renovation last year with my family and 2 young children so been quite busy. But now that the house is done, 2016 will be all about getting the garden done and that mean a new shed.... which has to have space for the telescope. The old shed was a simple 7x4, so it makes sense to upgrade to 13x7 doesn't it?! A small spot for the lawn mower and the rest for the scope plus maybe a warm room. Still working on exact plan and dimensions so I will start posting more soon and keen to get feedback. One thing for sure is I've decided to build it from scratch rather than buy. just much more fun. One first question is wether i need a concrete slab or concrete foundations or i can simply lay it on top of stone tiles. The garden is well protected so not worried about wind. Thoughts? manu
  9. Hello all, As the title suggests, I am making some plans of building an Arduino powered dew heater. Lately the dew on my telescope has stopped me in my tracks halfway through the night so its time to build some dew heaters. I want the buildup to be very simplistic in design with as little wires and as basic as possible. So far I have the basic supplies and ideas for it. In the sketch below is a very simplistic view of what i have in mind. I am looking at making 4 dew heaters, 1 for either the 250PDS or the ES triplet, 1 for the guide-scope, 2 as Spare or eyepiece heater. They are connected to the control box via a cinch connector, inside the control box we have 4 TIP transistors to switch the dew heaters on/off. These TIP120 transistors are cooled by some air vents in the box and controlled by the Arduino. The temperature sensors will be 1-wire devices which will be able to measure the heat of the dew band. To make sure it does not overheat. An external DHT22 will measure the outside temperature and calculate the Dew-point with the temperature and humidity. With this dew point and the temperature on the temperature probes we can calculate when to turn on the dew heaters. The dew heaters will be controlled via PWM. They will be made of NiChrome wire for the 250PDS and resistors on the smaller triplet and guide-scope. To prevent the Dew-Heaters from short-circuit or over-heating we also plan to place a fuse between the TIP120 and the Dew-Heaters themselves. This fuse will be of around 3.75A. (can be changed at a later point) I added a simple scheme to show what I mean. For the sharp people, in one of the pictures is a Arduino Uno, we chose to use this as it is bigger and a base for future Arduino projects. We will keep everyone here updated as the project develops and gets more automated! Clear Skies! Buikimaging
  10. Hi all, Pretty often I read about people having issues that may be related to backlash in DEC or RA, and I would like to offer a very simple and effective cure for it. I have done it on my HEQ5 Pro but surely it can be modified for any mount that needs it. With this simple fix, I can live with a rather big backlash (with no risk for binding in freezing temperatures). For DEC, I always balance carefully (neither front nor back heavy). Then I stretch the coil spring until it has a small impact on the DEC balance (and later in the evening I eventually forget about loosening it when I slew away... so you will need some replacement springs. It took maybe 10+ of such mistakes until I stopped forgetting...). The bracket is only attached with double sided tape (on three sides), but the black maintenance plug (not original) also supports it. RA is usually OK with just the standard method "East Heavy", but occationally the scope is poing due west or east (counterweights pointing north) and then there is no "East Heavy" impact. That is when I use this: It´s a little hard to see in the pictures, but I get a momentum in RA (in reverse to tracking direction) when I tighten the string. Now, I happen to have the Rowan belt mod which includes a thick nylon spacer inside the gear cover, and that is a good thing here because it adds to the momentum. I usually hook it up an hour or two before the CW bar points due north. Then when it has well past north I will stop the camera, remove the backlash killer and re-adjust "East Heavy". EDIT: (Sorry, English is my second language...) Should be a torque, not momentum. Ragnar
  11. Hi there, can anyone recommend the optimum length for a pair of dew shields for my 15x85 binoculars. Kind Rebards Paul J.
  12. Now the colder and damper nights are closing in I've found that I need to wipe off dew on my Celestron StarPointer pro finder quite often as it is pretty exposed to the elements normally (see third photo below), so I set about making a home made dew shield with some foam sheet (£1), and some Velcro (£2.50) to hold it in place. The results are below, which whilst not maybe a work of art does the job of keeping dew off the finder, and allows access to the controls on it still too. Total cost £3.50
  13. This post is about what I did during the British Monsoon. I have not many techniques to share here. It just want to encourage others that want to be able to look at the sun with a low budget (£25) and safe Solar filter. I was able to make one filter for my scope (102mm) and two small ones for my binoculars (2x 50mm). Actually you can produce 2 sets and share the cost with a friend. Only £12.50 for a set of filters, scope and binos. Materials Baader Astrosolar Filter Film A4 size - £23 One thick cardboard - recycled One thin cardboard - recycled from filter's posting package. Bendable card - £1.29 Masking tape - daughter's school kit One A4 sheet - daughter's school kit Tools Cardboard knife Sealer tape Scissors One CD and tin 1- Cut the A4 sheet in half and use it as model to cut the thick cardboard, the thin cardboard and the baader film filter. 2- You only need to cut circles in the cardboards. They will be the film holders. You can use the film square as it is. 3- Use the CD (102mm) to draw a big circle and a can around 50mm diameter to draw the small circles. Spread the circles wisely so there is enough space for the film to cover the circle, and expands until close to the edge of the cardboard. 4- The film holder is going to be a sandwich of one thick cardboard, the thin cardboard and the film filter in the middle. 5- Before sticking the film to the holder, remember to remove the fine translucency plastic that covers the filter on the side that is not protected by the tissue paper that comes with it. 6- Cut three stripes in the bendable cardboard, two inches or 5cm each. And one stripe of one inch or 2.5 cm for the binos.Use these stripes to make a tube that will fit to the scope/ binos. Just tape it as you circle the aperture of your scope/binos. 7- Use the tapes to put together the film, film holders and tubes. 8- To avoid the filters touching each other, fit the filters in different levels in the binos objective. I already tried it and I am very happy with the result. Any question please let me know. Kind regards
  14. It's about time that I got together a thread describing my rebuild of my old Orion Optics SPX350. I'd bought this a *long* time ago with a mind to doing it up to use for AP, but then house move, life, etc meant it sat around doing not a lot for a long time. When I came to use it, I got some good results, esp on planetary work, but also found that under the weight of the heavier SBIG CCD, the thin tube didn't hold collimation particularly well. Here it was: So, eventually, I decided to have a rebuild. I plumped for a truss tube over a remount inside a carbon tube. Not sure whether carbon tube would have been cheaper now though to be honest! As the scope is mounted on an EQ mount (my Losmandy Titan), it needed to have a central brace, and so I shamelessly borrowed many ideas from Rolf Olsen's excellent scopes (see: https://www.rolfolsenastrophotography.com). It started with the three rings - these were routed out of 21mm Baltic Birch Ply (sourced free from a mate who works in wood sales...). Internal diameter is 390mm. Onto these were mounted a new Orion 9 point primary cell (to replace the naff original 3-point cell) - shown here without any connecting hardware!): and with a bit of 1.5" aluminium tube, some drilling and making of small recesses using a spade bit, a secondary cage was constructed -- again without the final countersunk parts and connecting hardware: To be continued!!
  15. Took the bull by the horns and done the power modification on my Eq6 pro to connect via the 2pin connector , bit nerve racking haven’t really done much soldering before ,managed to do soldering without frying anything, used Blu-tac to isolate surrounding area so I didn’t solder anything I shouldn’t have , mount powered up checked slewing with handset , steady red light voltage reading 14v dropping to 13.9v slewing phew ?
  16. I have several parts, motors, and an arduino based AstroEQ controller that I don't use and maybe they could be useful to someone else. Btw I currently live in Turkey and I will ship everything with registered post from here. It should take approximately 2-3 weeks to reach to UK or other parts of Europe. I can accept payments from Paypal and also UK bank transfer. First, I have the arduino based controller. I have put it in a plastic project box. Pretty much everything is connected by jumper cables and the stepper drivers are on a breadbox. So it would be possible to change the casing or the individual parts rather easily. The DRV8825 stepper drivers are fast decay modded so they won't jump steps with lower voltage motors. I have installed the latest firmware that Tom has put on the website. If you want I can also adjust the voltage on the drivers before shipping depending on your setup. I'm asking £20 for it and £7 for shipping. Next I have two nema17 0.9 degree 6V 0.8A steppers. I have attached RJ11 female jacks for connectivity. £15 each and £7 for shipping. Both of them are sold. I also have a Nema14 1.8 degree 4.6V 0.8A stepper. Again I have put a RJ11 female jack. Price £10 and £5 for shipping. I've two handmade motor brackets for EQ5 (or equivalent) mounts. One for Nema 14 motors and the other for nema17. I have used the nema17 for RA and Nema14 for DEC. I'm asking £7 each and £5 for shipping. I have GT2 pulleys and belts. Two 40teeth and two 16teeth. 40s are bored to 6mm and 16s are 5mm, so they will fit the EQ5 worm and the stepper motor shafts. That would make a gear ratio of 2.5. I've included two GT2 140mm belts, which worked with my setup by adjusting the space a bit. I'm not willing to split this as the shipping cost would be more than the parts. As a whole I'm asking for £15 and £5 for shipping. Sold Finally, I two 2 meter cables with RJ11 jacks. From my experience when the standard thin phone cables are too long sometimes the motors don't function properly. Hence, I've used ticker cables with these connectors. £10 for total of two cables. £5 for shipping. If I ship multiple items together it will be cheaper. I'm also open to offers. And please ask me if you need more info.
  17. From the album: Astronomical Equipment

    I finally received enough of the parts for my DIY dew control system to begin making the first one.
  18. Pappy Nick

    It's ma Dob

    From the album: Pappy Nick

    It's finally been done !!!!!
  19. From the album: Meade 5000 APO 80mm focuser

    Brass wire for tensioning
  20. I have searched SGL for a tutorial incase this has been covered so forgive me if it has. I've also searched the web in general and couldn't find a full tutorial to do this, so i have collated a couple of tutorials that make it work. I have managed to get SkySafari to work with a £32 ish Raspberry Pi3 and the cable that came with my scope with a usb to serial converter - the same things you need for connecting to a PC. It allows me to control the scope using the SkySafari Plus app on my tablet or phone AND it creates a wifi hotspot on the Raspberry Pi so it doesnt have to be on a network to work. This also turns the pi into a natty mini wireless router which is handy if you travel since it gives you a private wireless network when plugged into hotel wired internet ? ***STANDARD DISCLAIMER*** I AM NOT RESPONSIBLE FOR ANY DAMAGE THAT MAY OCCUR TO YOUR HARDWARE BY FOLLOWING THIS POST OR ANYTHING LINKED TO THIS POST It takes about 30 mins to do the tinkering, make sure you use the latest LITE version of raspbian. You need: Raspberry Pi 3 Portable power to it (preferably) Raspbian Lite Image file Appropriate cables to connect your Telescope to it via USB Computer connected to network Network cable to connect Raspberry Pi for initial setup A GoTo / Push To etc telescope mount compatible with SkySafari Plus / Pro A nice case for the Raspberry Pi You need to know a little about accessing the Raspberry Pi by SSH. For windows, use Win32 Disk Imager to burn the latest Raspbian LITE image to a micro sd card. Open the card on the pc (called boot) and make a blank file on it called 'ssh' - no file extension. This enables ssh access automatically. Stick it in your Pi and plug it into your network router and a power source. Find its ip address - i log into my router by typing its ip address into a web browser and look at connected devices, there are other methods though. I use a program called Putty to ssh. There are many tutorials on how to do the above and it isnt as hard as it first seems. I used 2 tutorials to do this and i will link to them directly as the original authors explain it better than me. The first one is muuuch longer than the second which is just 3 steps so bare with it. ***NOTE*** When the first tutorial suggests a reboot after the upgrade, DO IT! Then ssh back into the Pi and continue. Don't bother rebooting after tutorial 1 either. Tutorial 1 - Turn Raspberry Pi into a portable wifi hotspot See 'CONNECTING' after doing step 2 in the next tutorial to actually connect to the scope as what you have just done changes it a bit. Tutorial 2 - Make it talk to SkySafari App and the 'Scope You can now unplug the pi from your router. Plug your USB to serial adapter into the pi, your telescope cable into that and connect it to your scope as you would do with a pc (mine is into the AutoStar hand box) and use it as a stand alone adapter just like the £200 SkyFi adapter! CONNECTING: To connect SkySafari to the pi you simply connect your tablet or phone to the pi's network like you would any other wifi network, i called mine Scope, connect using the security key / password you made up in tutorial 1. Open SkySafari and follow step 3 in the second tutorial but with IP address 192.168.0.10 - the port is still 4000 (unless you changed it) If you are at home and your cable is long enough to reach your router you can plug the pi into that and use your home internet too - which you cant do with the SkyFi adapter! I am going to shorten my serial cable to make it a neater package, i can always solder new plus to make an extension if i ever need one. I am also working on finding out how to make it share usb internet so a 4g dongle can be plugged into it when out and about since when you connect to the pi's wifi in the field you will not have internet on the device connected to it. Also the Pi could possibly be used for imaging or tracking, someone on here will probably know more on this.
  21. Hello reader, Appreciate your time to read that topic. Have you ever tried 3D printing tech to create/design any of your astro components that may substitute expensive ones?. I'm curious to know your thoughts about it. Thankfully, Bamo
  22. theropod

    Hi Everyone

    Hey all, Last summer I figured out how to capture images of meteors during the Perseid shower using my iPhone 6+ and the app NightCap Pro. Since then I have managed to grab over 200 of these speed freaks. I built a barn door tracker and learned how to drive it with an Arduino, Easy Driver and a salvaged bipolar stepper motor from a dead Epson printer. After numerous adjustments of the code to get the speed just so I can get 5 minute shots with little to no trailing in the wide field work I am doing. The tracker can run for about 5 hours before it needs to be rewound to the starting point. The variable interval setting in NightCap Pro is perfect for the kind of images I am after. Attached is one of those Perseids that started this whole affair well beffore my barn door tracker came to be. Of course this was enough to cause an addiction, and I bought a little Celestron C90 mak. I love the scope, even though it isn't an earth based Hubble. The erector prism is a joke as is the tripod and finder scope, but the main scope is a fine little machine. So far I have managed a few fair shots of Jupiter and Saturn, but my barn door tracker is not sturdy enough to carry the scope. In an attempt to overcome this I bought the iOptron Skytracker Pro and matching ball head. Let me just say I am far from impressed. This tracker is mounted on a 1/4" plate of aluminum which is in turn mounted to a water filled 55 gallon drum that serves as a large pier. My barn door tracker is also mounted to this plastic drum, and the barrel sits on a thick bed of crushed limestone. I also drove steel T posts into the ground nearly level with the barrel top, and then clamped all this together with a 1 ton ratchet strap. No matter how hard I crank down the setting knobs on the ball head the scope droops slowly to plumb. When I just mount my iPhone to the ball head this issue doesn't arise, and I have made 25 minute exposures with nice crisp stars. The scope is supposed to be well within the capacity of the tracker and ball head, but apparently is not. So, my next purchase, after months of research, is going to be the Celestron Advanced VX mount, and I may give the iOptron gear to a deserving kid. I don't care about serious deep field work, but the C90 can easily resolve more faint objects than I thought it would. Resolving the major moons of Jupiter is a trvial endeavor. The narrow field of view doesn't bother me at all. Perhaps I will buy a larger scope in a year or so and use the C90 as a guider. Some personal info: I am a retired 63 year old man and live off the grid in north central Arkansas Ozark mountains on 60 acres with my wife of 24 years. In a former life I was the executive director of a small natural history musem that focused on the terrestrial fuana of the very latest Cretaceous of the Hell Creek formation in South Dakota (when non-avian dinosaurs became extinct). Currently I am attempting to recover from a broken fibula that happened the second monday of March, but had a CAT scan last Friday in preparation for reconstruction surgery later this week. The breaks, yes multiple fractures, have failed to reunite as they should. This, of course, will mean a restart of the mending and effectively put my sky watching in a bind for another 6-8 weeks. Even if I am back on crutches I will be ready for the Perseid shower, and will probably visit with my son in Oregon to watch the total solar eclipse in August. So, here I am and eager to absorb the collective knowledge I have already seen is a commonality on your fine forum. Thanks for having me. Perhaps I can even contribute a few tidbits from time to time. Roger
  23. Part 1: What complicated electronicality goes into your average GoTo mount? Answer: Not as much as you’d think! In fact, that’s it. The above picture comprises the entire guts of an early generation (circa 2000) Celestron Nexstar GoTo Mount that accompanied a 90mm refractor scope. This particular example is a dead one, but it’s enough to show us what’s going on. So what have we got there? Let’s break it down… The Control Board Ooohhh… it’s got chips on it. Must be clever. No. Ultimately there are 3x components here that do the work. On the right are 2x XIC0014 oscillators with a 4mhz crystal each. We can summarise their job as: timing. These keep tabs on timing for signals going to and from each motor. On the left in the middle we have a 74HC240D. This is an octal line driver which takes 8 incoming teensy pulse signals and amplifies them into 8 larger pulse signals. In the lower left corner we have an L293DD. This is a part of interest. This is a 4channel H-Bridge motor driver. The pins on the right hand edge are for the hand controller. The pins on the left hand edge are for the Azimuth motor (left & right horizontal motion). The pins on the top edge are for the Altitude motor (up & down vertical motion). That’s a lot of pins for a motor tho… There’s also a MOSFET up top, which will be involved in regulating the incoming 12v DC down to 5v DC to run the electronics. The Handset board Nothing complicated here. It’s an RJ45 socket, mounted on a board along with the 12v power connector. Black & Red are 12v, which goes up to the handset, and across to the controller. The remaining 4 wires carry TTL signals from the handset to the control board. The Motors (x2) The mount contains 2x motors. These are DC controlled, and rely on 2 wires only. So what are the rest of the wires (6x) for? Feedback! Mounted to the rear of each motor is an optical encoder wheel. The black box at the top has an LED mounted in it, pointing at a light sensor. In between these, the wheel passes. Note the slots. The sensor detects the light being blocked and unblocked by the wheel, and converts these into pulses. So there are 2 wires providing Grnd and 3.3v to the LED. The encoder itself outputs one pulse for each slot. This is our speed signal (by counting pulses over a period of time), and by storing the count they can be used for position also. That’s one wire. It also outputs a direction signal. This is a high or low (on or off) signal. If the output is high, the motor is moving forwards. If the output is low, it’s moving backwards. That’s another wire. The encoder circuit needs power… 5v & grnd. That’s another 2 wires, giving our 6. Gearbox… Each motor mounts to a gearbox. I haven’t a clue of it’s ratio, but from the surface dimples we can see that it contains an input gear, which translates it’s motion through 4 other gears, then to the output gear on the other side… …which in typical fashion is smothered with the stickiest cheap & nasty grease known to man. This drives the transmission wheel, which uses a friction plate to move the relevant part of the actual mount. Again, this is liberally smeared in sticky cheap mank. Summary All the control board does is translate signals from the handset directly into drive commands for the motors. ALL the intelligence is in the handset. A bit of diagnosis tells me that the handset for this mount has been fried, along with the control board, but both motors and encoders are in perfect working order, so how can we resurrect this setup? Seeing as all the control board is is a multi channel H Bridge motor driver and feedback sensor board, we can replace the lot with a Raspberry Pi and a few bits. The Raspberry Pi’s GPIO pins can quite happily output 2 channels of PWM to control the motors themselves, and can easily receive 4 channels worth (2 per motor encoder) of feedback pulses. All we need to do is get power to everything. Conveniently, all the bits needed can be picked up for a grand total of sod all (or less) from most robotics hobby places. I already have a veritable mountain of Raspberry Pi boards so I don’t need to acquire one. These cost me £18 each. To hook up the motors, I’ll need a dual channel Pi motor driver board, so I’ve opted for a DRV8355-based kit which can take a 12v DC power supply to run the motors, and with the addition of a 5v step-down board it can also power the Raspberry Pi itself which in turn can power the encoder boards (which also run at 5v). The Pi also provides a 3.3v output which can power the LEDs on the encoder boards. These two components from the provided links total £12.36 inc shipping. Add the cost of the Pi, and that’s £30.36 for a replacement control board.
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