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I bought an Opticstar 2" Manual Filter Wheel and the plan is to stick an arduino controlled stepper motor on the wheel perimeter to turn it. Magnets and hall effect switches will be used to keep track of the position and which filter is active. The mechanical design is done using the open source apps LibreCAD and FreeCAD. G-code for my CNC mill is produced using HeeksCAD and the mill itself is controlled by LinuxCNC. Electronic design is done using the awesome KiCad which recently has had a massive boost by the propeller heads at CERN. The mechanics is almost done. Still need to etch the PCB and put it together before the real fun begins writing the firmware Clear skies, K

Hi I am trying to control my Skytee via stepper motors using a joystick joystick, Ive found a handy YouTube video that controls 2 small stepper motors but these will not be powerful enough, I’m looking to use Nema17 motors via a more powerful driver, just not sure what pins from Arduino to Stepper driver to plug into as in the image attached sketch. Assuming I can replace the ‘ULN2003A ‘ controller with ‘DM332T’ and power the new bigger driver directly with 12v and miss out the 5v power wires going to the ULN2003A that is in the sketch. Appreciate any help. Regards Guy

Been working on this motorised flap flat panel for quite some time already. Thought I'd finally post something about it as I just got the flap opening and closing properly for the first time. I initially designed this around the 28BYJ-48 stepper but that just turned out to be too weak. I did manage it to make it move by converting a 5V version to bipolar mode and driving it with 12V. But as soon as you removed power the gravity would take over and the flap would be a bit too flappy... Keeping the motor energised continuously would have made it too hot over time and it probably would have not lasted very long so I decided to go with a high torque servo instead. This one is using a Hiwonder LDX-227 servo. Seems plenty strong for this application. The flat panel itself is still work in progress. My original idea was to shine the light straight to the edges of the diffusing perspex but that didn't work out very well so I started experimenting with other ideas. At the moment the LED strip ring is hidden behind the diffusing perspex and reflecting off a reflector (aluminum foil on a concave surface). To the eye it looks pretty flat but if I take a photo of it and stretch the levels, you'll start to see a bit of a gradient. Whether this is a problem, I'm not sure... More about this later...

This is actually a project I started back in 2015 but it's been hibernating on the shelf for a number of years (i.e. way too long). Up until now I've been just running my dew heaters full on without any controllers whatsoever. This has not caused me any trouble until recently. I changed the secondary mirror on my Newtonian to a bigger one and also the way it was mounted and heated. It turned out that heating the secondary this way full blast is not a good idea as it would warp the mirror ever so slightly to cause astigmatism. Anyway, here I am trying to complete a project that is way overdue... My idea is to measure the ambient temperature and relative humidity with a DHT22 sensor and calculate a dew point from that with an Arduino which would then in turn control a number of dew heaters (max 4) while measuring their temperatures. The idea is that with empirical experiments I could come up with reliable offsets to keep the optics a couple of degrees above the dew point to prevent fogging. How successful this is going to be; I have no idea... As a bonus the device will also measure the atmospheric pressure. Some photos of where I am at the moment: Here's a KiCad 3D preview of the board(s) I designed Decided to have the PCBs made by JLCPCB for me. The minimum order with them is 5 pieces so if this turns out to be a successful project, I'll have four extra PCB sets available. PM me if you're interested... Here's the real deal soldered. Not too far from the 3D preview All wired up ready for testing and further development. I intend to make this into an INDI device as well so I can log the measurement data...

My attempts at SID monitoring have been languishing for a while due to radio problems, though I have been getting to grips with Arduino and even had a go at building my own. In order to move things along I went to the UKRAA stand at Astrofest and bought the VLF radio kit, their signal generator and the 15V power supply. Last weekend I soldered the board. It wasn’t too difficult following their instructions which are pretty clear. The only fiddly bit was soldering on an SMD capacitor but they also give you a through-hole one as well. Initial tests suggest it is working but I will have a better idea when it is all connected. This weekend I have been working on the housing and hopefully tomorrow get the leads soldered. From left to right will be led power, 15V in, 15V out, antenna in, then analogue -ve and +ve (can be 5V or 2.5V). I am building it as-is, so the first iteration will have the radio running off mains power and in turn the radio will power the Arduino. That seems a bit backwards but I would just like to get logging data. For the time being it will write to an SD card, but the Arduino MKR 1010 looks rather good and comes with WiFi and encryption. That though, is a long way off..! Anyway, this shows progress so far.

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 .

Hi, I want to display FWHM values on a homemade focuser handset over USB from either BYN or Metaguide. Does anyone know if these programs even output their data, and can it be obtained? I have an arduino, and access to some good programmers thankfully.

This will be a thread detailing some of the changes and additions I will be doing to my ASC/Weather Station project. This is version 2.0 as I'll be making some very big changes from the initial project and I think continuing on in the existing thread would not have made much sense. So, I still want to use an APS size sensor as after seeing the quality and light capturing capabilities of the now defunct Opticstar DS-616C XL camera and Meike lens I simply cannot go back to using a smaller lens/sensor combination. One thing is certain, I won't be paying £400 or potentially more for another APS astro sized camera so with that in mind I plan on heavily modifying a Nikon D50 DLSR and use the same lens. I chose the D50 primarily due to it having a CCD sensor (ICX453AQ) very close in specs to the one in the Opticstar (ICX413AQ) and the fact that I got a hold of a fully working body for £25. Now there's a few issues with going down the DSLR route which I plan on addressing as follows: The oversized camera body can be stripped down to bare essentials and fitted in the existing case with some moving of parts around Uncooled, the sensor is quite noisy so to cool it I plan on using the existing Opticstar enclosure with the TEC and hopefully get it purged with Argon to avoid dew formation. Also, since the box will need to be completely sealed to achieve this, there's simply not enough room inside for the main board to which the sensor connects to. The only way around this is using an 39pin 150mm long FPC extension which I managed to find and will be arriving shortly. This means I can have the sensor completely sealed with enough slack in the connection to place the mainboard anywhere I want. The D50 uses the NEF file extension as a "RAW" file format but it's not truly RAW and a heavy median filter is applied to all long exposure images to smooth out the noise. It works great for day to day shots, but in an application such as mine it'll most probably eliminate or severely affect my stars as most of them at the FL I'll be using the camera at will be a few pixels across and the Nikon median filter is very aggressive with such small features. The way around this is what's commonly known as Mode 3 on Nikons. Nikons have a additional Noise Reduction mode which takes the long exposure light first then straight after an equal length dark with the shutter closed, then applies the dark on the light and you get a further noise reduced image which again works very well, but not so much for AP. With mode 3 you essentially have the NR feature on and take an exposure but then immediately shut down the camera after the light has finished exposing. What this does is it causes the camera to dump a REAL RAW image onto the SD card without applying the median filter OR the Noise Reduction process. This obviously results in a much noisier image as expected, but all the stars will still be there and the image in this way can then be dark-subtracted and processed to my liking. I'll post some test shots I've taken to illustrate this. The D50 uses a hybrid shutter, both the CCD electronic shutter and mechanical shutter are used depending I think on the exposure length. If a high enough exposure is used, from what I understand, one can use exclusively the electronic shutter, but for longer exposures the shutters work in conjunction. Now I know the ICX413AQ in the Opticstar is more than capable of taking long exposures solely with its electronic shutter despite the fact that in its datasheet they recommend a mechanical shutter for proper use. So, my thinking is since the D50's sensor is similar to the ICX413AQ the only thing preventing the camera from being able to take any exposure using exclusively the electronic shutter is that its mechanical shutter is in the way and I don't think that the camera would prevent the CCD electronic global shutter itself to still open and close when required. However, this is all a theory at the moment and the only way to confirm it is to test the camera with the sensor outside when the FPC cable arrives. More on this later... In terms of capture software available, the D50 is actually very poor and I could only get digiCamControl to see and control the camera via USB. But I won't be using this as when the camera is hooked up to the PC its SD card is identified as a storage drive and the camera can be used as it would normally with the images appearing on the drive after being written to the SD! Since I'm using my VB app to process the images I would just point the app to that folder and should work. That's all I can think of for now but if and when new ones come up I'll add them here. Next I'll be describing some of the other changes planned.

My diy Onstep GoTo controller is basically an Arduino Mega 2560 with a RAMPS 1.5 shield, rated for 12V normal, 20V max & uses about 2A max. It is powered from a 12V car battery. The lead has crocodile clips at the battery & connects to 5A screw terminals on the RAMPS. When I "power-up" by connecting the clips there is a spark at the terminal. This is expected, but does the sparking reduce the life of my electronics? If so is there a cheap/simple way to reduce or prevent this? I know I could put a switch in the lead but I assume the sparking would then happen inside the switch, making no difference.

Hi, I've been working on a DIY fan for my 10" Skywatcher newt. My plan is to measure the ambient temperature and the mirror temperature with two separate thermistors and control the fan speed depending on the temperature difference. My question is, does it make sense to use the fan if for some reason the ambient temperature is higher than the mirror? The fan is sucking the air out the tube at the moment.

Hi, I would like to share my design of a smart barn door tracker. It is a simple to build isosceles barn door tracker with tangent error correction through a Arduino micro-controller. I have shared all the details about the tracker including the mechanical design, electrical circuit and the software source code here: https://barndoor.spa...ference-design/ If you are interested in the math and other details about a barn door tracker, more details are there in the blog. Also find an online calculator which helps in calculating various parameters while designing a barn door tracker. The blog is here: https://barndoor.space/ M46 and M47 shot with this tracker. 135mm lens, ISO800, 15sec X 200 subs (50 minutes) exposure. Cannon 500D. Comments and suggestions most welcome! Regards, Arun

Hi Guys, I have an old C8-N with drives and a handset with an ST4 port. I'm using an Arduino to do small jobs around my setup like exposure control, electronic focusing, guiding and small GOTOs through the handset (large ones take too long). The first three work nicely, by my GOTO is all over the place and I've just realised that whether I'm looking toward the Eastern horizon or the Western one must mean that I need to invert my Dec movements. Is this the case? Is this the only effect of the meridian flip? The RA axis keeps on chugging (and I don't mean collecting for charity) in the same old direction, but Dec needs be inverted. Is there a proper name for these two modes, like "Western mode" and "Eastern mode", or before and after midnight? What else should I look out for? Thanks Steve.

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.

Hi Guys, I have a wonderful Arduino that does everything for me. It focuses, exposes, guides, does GOTO and a myriad of other things. It also give me the weather, well really only temperature and humidity. But from that it works out the dew point. Is there any point in waiting until the external temp drops below the dew point before turning on the dew heaters, or should I just leave them on all the time? This is what the output looks like now: "UTC: 2017/07/12 20:22:14 | 17 Deg C | 70 % humidity | Dew point = 11.5 Deg C " It keeps monitoring the conditions every few minutes and it can turn the heater on for me if I like, but should I bother? Maybe it's better on all the time. What do you think? Regards Steve

Imaging season is still a few weeks away up here, but I've started dusting of my gear and upgrading some parts. One step closer to automation is a motor focuser, and I opted for a budget solution. I bought a SkyWatcher DC focuser and built a computer control for it. Since I use INDI for my automation, I had to find a way to connect the focuser to indiserver. A first thought was to use the INDIduino code, but after some coding and testing I found out that this code is very limited and not really supported by indi clients. The Ekos/Kstars focus module can't be used for focus control if you use INDIduino, apparently. But then I stumbled upon an Arduino solution that emulates the MoonLite focuser (http://www.indilib.org/forum/general/283-moonlite-focuser-protocol.html). Unfortunately, this protocol is for a focuser with a stepper motor, whereas the SkyWatcher has a geared DC motor. I had already rewritten some code from stepper to (geared) DC motor, so it was easy to adapt this to the MoonLite based code. My solution consists of the following: hardware: - SkyWatcher DC focuser (only the motor is used, the handbox is replaced by the Arduino) - Arduino UNO - Velleman motor controller shield for Arduino - 9 V power adapter to power the shield - Raspberry Pi software: - Arduino sketch with Geared Motor library (see below for link) - INDI server on RPi, and client (Ekos/Kstars) on Windows I've tested this setup on my SkyWatcher Explorer 150PDS and it runs fine. Unfortunately I haven't been able to test the autofocus, due to absence of astrodarkness and clear skies. Since a DC focuser has no knowledge about the position of the actual focuser, the software assumes that position '0' is all the way in. Maximum position is 25000 for my setup. By default, focus is increased by 100 steps, which is supposed to be 100 ms of motor drive. BTW, the code is in my GitHub repository: https://github.com/wberlo/Arduino_Moonlite_Focuser

I've been whiling away my shipping wait for my hardware by watching and reading about Arduino and Stepper Motor control (Specifically). I was watching one rather informative video where the author hit on another library for the Arduino, AccelStepper. It appears to be a bit simpler than regular Arduino coding, which was attractive to me. But what really brought me running was that it can accelerate and decelerate on either end of the command. Think of it being a Soft Start for a stepper motor running your focuser, or a Filter Wheel. Soft Start? Yes, a Soft Start, and also a Soft Stop. Making your stepper motor gently begin to move, traveling to your selected point, then slowing the travel so it coasts in to what you requested. Soft Start is becoming quite common for a lot of motor driven devices. So my thoughts on it were to program my upcoming Arduino projects with my own Soft Start and Soft Stop to bring the focuser to Step XXX and when trying to toy in a best focus, the automatic Soft Start could aid in getting gentler adjustments. I bounced this idea off of my friend and he said that ramping speed was more for CNC machines and the like. And that tweaking in a focuser was more like around 70 steps to get the human eye to see the difference. I don't know (yet), but it seemed to me making any command gentler on the overall equipment might be a better idea. Arduino (I've been led to believe) doesn't have this Soft Start - Soft Stop in their library yet. If you would like, Here are the links to this idea: The Maker Show by Bret Stateham. If you scroll down on this page, there are quick links to the different parts he covers, including the AccelStepper part. Quick Link to the AccellStepper Part. Or a bit before, where he refers to the Library, and where this software will be if you choose to download it for your Arduino Programming. I did, so it is there when I get my hardware here and actually begin my developing. (I prefer to have things in front of me as I prototype. I'm a hands on kinda guy.) I searched to see if this had been posted here, but found nothing. So I thought I'd offer it up to anyone who might be interested. OK, back to hammering on my brain. (Think: A BB in a Boxcar.)

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

Hi all I have an idea for a little fun project that I hope will get me a good inroad into Arduino and electronics - but need a starting hand! So, what I'm thinking is to build a portable power box that houses the USB ports, power switches for the mount and camera, etc, but also has a 2-line LCD display showing a variety of different measurements from the system - Voltage, Current, Temperature, Dew Point, LST, and eventually reading the mount for DEC and RA position. Possibly!! The power box has a 7-port 12v USB hub, 1 USB input, 2 x 12v inputs each one supplying 3 outputs. There will be a button to cycle through the different sets of readings. One of the USB ports will be used for the Arduino, the others will be mount, camera, guide camera, focuser and SQM Reader. One of the 12v supplies will feed the mount and camera, the other will be for the dew controller and any other 'dirty' outputs needed. Power supplies will be a 13.8v Maplin bench supply (5amp, 7amp burst) - for the mount and camera side, and then another 12v 5amp for the 2nd inputs (don't have this yet...). So, first step is get the Arduino to read the voltage and current from the two circuits. So, from digging around, I think an ACS712 is what I need to measure the current. Now the questions... 1) Are the eBay ACS712's OK to use? 2) For the voltage measurement, will a voltage divider be sufficient, or should I look for a dedicated module? Absolute accuracy is not vital I guess... 3) Other than fuses on all the lines, is there anything else I should look at for current protection for the Arduino? I don't have a shopping list yet as I still have lots to think about, of course, so any recommendations on the LCD (HD44780 based one?), or anything else, feel free to shout! Thx

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.

I thought I would share with you last summer's project to add set-point cooling to my DSLR. It took about 3 months and wasn't actually required much over the cold winter months. I've made a few minor changes since the winter. The original white-on-blue display packed up so I replaced it with this black-on-green one. And the original ball-bearing fan introduced vibration when using my SCT (not apparent on my other scopes), so I've replaced it with a MagLev/vapo type. Unfortunately I haven't had any clear skies to test the new fan... My main design criteria were: Cold-finger/peltier cooling As little 'destruction/deconstruction' of the camera as possible - I wanted it to still look like a DSLR Achieve 5-10 C set-point cooling, as I felt this gave acceptable low noise Include a dew heater/indicator for the front filter Arduino controlled with display to provide useful feedback on settings and simple controls I give due credit to Gina and Rowland Cheshire, having read their many inspirational posts on cooling (both here and on Ice in space) which helped me to hone my design. Image with the camera shows fan-heatsink-peltier-bracket construction. The connection box is screwed to the tripod mounting. The white sensor measures ambient temperature and RH. The controller images show approaching the set-point and at set-point. A red LED above the main display lights up when the dew heater is active. The display shows: Set = desired set-point temperature CMOS = temperature of cold-finger close to sensor Fltr = temperature of front filter Dew = number of degrees above the dew point to maintain the dew heater TEC = heatsink temperature (hot side of peltier) PWM = percentage output sent to the peltier (I've limited it to 90% max) Am = ambient temperature, DP= dew point, RH = relative humidity At some point I will tidy the heatsink side to conceal the cables, etc. John

Well after making the 4th PCB for my dew controller and now using an Arduino Mega with a shield to mount all the regulators/MOSFETs etc I was struggling to get accuracy when drilling the holes for the components. Drilling 34 holes for an IDC connector by eye wasn't good enough and was difficult to mount the component. I bit the bullet and got hold of a Proxxon MF70 CNC Mill. It has only got a small bed but I already have a manual one and the accuracy of the table lead screws is very good with a nice solid cast iron base plus the size is convenient for table top use. I'm using an Arduino Uno with a ready made CNC shield of which 4 A4988 stepper motor drivers plug straight in with grbl software on the Uno After wiring up a test of the software (steep learning curve on G Code) using FlatCAM and bCNC - the X and Y axis homed on command but the Z axis carried on and hit the top of the pillar crushing the limit switch. Luckily Maplins stock these switches so replaced easily. Before connecting the Stepper I tested out the Z limit switch but the logic wasn't registering it. A simple button code showed that the arduino was seeing the switch change state so it must be something in the grbl code. After a lot of search and browsing the source code I found out why. The lasted version of grbl V0.9 changed the pin for the Z limit switch. The shield uses Pin 11 but this was swapped to Pin 12 to enable a PWM spindle control on Pin 11. After rewriting the code I had a working z axis homing command. So to my first CNC job was to mill out the plastic front panel for the box to house the control and PS. Unfortunately I had the spindle to fast so it started to melt the swarf which scuffed up the surface - but the good thing about CNC is that you can stop the job and clear the melted on swarf from the bit and carry on from where you started. Time wise it probably took a bit longer from designing in AutoCAD to creating the G Code to finishing the job but the cuts were accurate with none of the usual by hand mishaps and mis-shapen holes -- Mark

I've read through just about all of the threads relating to Arduino based focusers and building one is definitely something I'm going to have a go at. A 'version' I haven't seen yet is one using rotary encoders...so I'm guessing there's probably a reason for it! But here goes... My idea was to use 2 rotary encoders to control the stepper. One encoder for coarse focusing and the other one for fine adjustment. Something like this : In theory the coarse encoder would move the stepper a larger number of steps and the fine one would be single (or half) step. I did toy with the idea of using potentiometers (connected to the analogue inputs) instead of rotary encoders but thought the 360° rotation of the encoders would be more suitable. As my knowledge of programming is on a par with my guinea pig's, I'd like to know if the idea is feasible or not before attempting to blatantly copy and modify the various (rather brilliant) sketches and ideas from southerndiver357, yesyes, Gina etc. Any comments would be gratefully received.

I have been toying with the idea of upgrading to mono CCD imaging for a while, after spending a lot of time looking around the forums I have decided to go for it. I have decided to go for the Atik 460EX, being quite a large amount of money and the need for a filter wheel to go with it I have decided to try and build the filter wheel. It will need to be as thin as possible to fit my newt, I will be using an Arduino to controll it and at a later date I might have a go at making it ascom compatible, but that will probably be pushing my abilitys too far! I have made a start with it, and there is still a long way to go, but I thought I would post my progress so far to see what input anyone has . I have started things off with a small stepper motor I salvaged from a printer, this had a small nylon gear on it so I punched a wheel from 3mm alloy at work and went about cutting the teeth to mesh with the gear. As luck would have it the gear matched up with the 1.25mm pitch of an M8 bolt, so I used an M8 spiral flute tap to cut the thread. I then made up a hub using a bearing I had, and had it anodised black so that i could be put together. This all went together ok but left me the problem of holding the 1.25" filters in place. I went in to my local telescope shop and managed to get some old eye piece barrels (thanks Charls ), then parted them off into 3mm thick sections. They will be glued into the wheel later to screw the filters in. I have now made a front and rear cover roughly to the shape and size I will need, they are held together with 16mm stand offs. I fitted the stepper to the case and gave it a try using the stepper focuser I made following the SGL automation design and code. The stepper motor is 12v 9.6 ohms motor, it turned the wheel with no problems and needed 22386 steps to turn the wheel one rotation, this took just under 6 secounds. I had to space the wheel 2mm from the hub to allow the motor to engage the wheel and allow enough space for the filters. I am now looking at sensors for the home position, I have ordered a hall sensor from here, http://www.hobbytron...l-effect-switch and some 2mm magnets from here, http://www.ebay.co.u...984.m1439.l2649 to try. I have also ordered an easydriver board to drive the stepper motor as the focuser setup worked so well with it. There is still a long way to go, I need to sort out the home position, I can then count steps to each fiter. The punched wheel is bowed from the punching, I think I will need to machine it from scratch, I wil get it all working with this wheel first. I will need to conect my skywatcher coma corrector to one side and the camera to the other, this will need M48 and M42 threaded adaptors making, but I am unable to cut metric threads on my lathe, so I will need to adapt some existing fittings or pay to have them cut! Any thoughts/ ideas are very welcome Thanks for looking Jason.

So, finally my DIY arduino SQM is finalized, it is not calibrated yet, but hang in there, i will do so in the near future... But first i want to point out that i didn't want any scientific grade SQM but just a simple tool that i can use to compare different photo-sites around my home-town here in Sweden Feel free to Use it as you want to, if you wan't to calibrate it, change the value at: const float A = 22.0; More pictures and code are available at SGL's Yahoo-site. The parts needed for this is: Arduino approx. 30USD Light to freq-sensor: TSL237 - electrical component shop 5 USD 0.1-0.01uF capacitator 20 degree lens - ebay 1USD UV/IR-cut filter between the lens and the sensor - ebay 1 USD Some kind of housing and cables/connectors The lens is mounted to a plastic cover with superglue, the UV/IR filter is mounted underneath it and underneath that, the sensor. The sensor has three connectors, one gnd, one vdd and one signal, so it quiet simple to connect, you should use a capacitator to stabilize the +5v. Here is a video of it how it works (not the best quality i'm afraid. And here is the code: The libraries you need is at the top of the code. // Author: Daniel Sundström and Ola Karlsson, Arvika, Sweden #include <FreqMeasure.h> #include <Math.h> #include <LiquidCrystal.h> float Msqm; const float A = 22.0; int buttonSQM = A2; int val = 0; int reading = 0; int percentage = 0; LiquidCrystal lcd (12, 11, 10, 9, 7, 6); void setup() { pinMode(buttonSQM, INPUT_PULLUP); digitalWrite(buttonSQM, HIGH); lcd.begin(16,2); Serial.begin(19200); } double sum=0; int count=0; void loop() { val = digitalRead(buttonSQM); if (val == LOW) { reading = 1; lcd.clear(); FreqMeasure.begin(); while(reading) { if (FreqMeasure.available()) { // average several reading together sum = sum + FreqMeasure.read(); count +=1; percentage = count/31.0*100.0; lcd.setCursor(0,0); lcd.print("Reading"); lcd.setCursor(8,0); lcd.print(percentage); lcd.setCursor(11,0); lcd.print("%"); if (count > 30) { double frequency = F_CPU / (sum / count); sum = 0; count = 0; Msqm = A - 2.5*log10(frequency); //Frequency to magnitudes/arcSecond2 formula lcd.clear(); lcd.setCursor(0,0); lcd.println("Mag/As2: "); lcd.setCursor(9,0); lcd.print(Msqm); delay(5000); lcd.clear(); reading = 0; FreqMeasure.end(); } } } } }

Can anyone offer advice or pointers for making a DC Stepdown Voltage Regulator? I would like to take a nominal 13V DC supply from a regulated transformer or Power Tank and provide 5V DC 1A (to power 2-3 arduino nano V3s) and 2V DC 6A outputs (which will provide power for a small TEC, via a Logic N Channel Mosfet - FQP30N06L). I'm keen to avoid too many wires, so ideally this would fit in a single project box with the controllers and not generate too much heat - but it could also be two small project boxes mounted back to back. Actually it might be useful to have a little more 5V to power a small USB hub.