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This page showcases what users have built with OnStep.

OnStep is being actively used for anything from EQ4 type consumer telescopes, all the way up to an 80cm Ritchey-Chretien in an observatory in Italy (that is 31 inches of aperture!).

If you did build a controller with OnStep, please subscribe to the mailing list, and post description and images as a reply to  this message. Or if you have a web site, post the information and pictures there, and reply with the links.

Equatorial Mounts

Equatorial mounts track the apparent movement of the sky using only one motor (on the Right Ascension axis). This axis is aligned with earth's rotation axis. Many of these mounts can be used for astrophotography, to varying degrees, specially when OnStep is used to tune the backlash and periodic error correction (PEC). Also, an OnStep controller can have an ST4 Auto Guiding port for precisely correcting tracking of an object.

  • User Alex F converted an EQ5 mount to OnStep using the BluePill Kit, TMC2209 drivers, 3:1 pulleys, 0.9degree 0.9A motors. He also compares his observations of the TMC2130 vs. TMC2209.
  • User soulvagabond converted an EQ5 mount to OnStep using the BluePill Kit, and TMC5160 drivers.
  • User pfloyd converted an Orion EQ3-2 mount to OnStep. He used Applied Motion HT23-399 200 step NEMA 23 1A motors, pulley reduction (60T to 20T 3:1 for RA, 40T to 20T 2:1 for DEC), MaxPCB2 and TMC21300.
  • Christan Kampf converted a CGE Pro mount  to OnStep. He used Quimat 200 step 1.7A motors, with 0.59Nm/ of torque, the MaxPCB2, and TMC2130. The pulleys are 60T and 20T for a 3:1 reduction. Custom metal brackets are planned. The original PEC and limit switches of the mount were reused for OnStep.
  • Marko Himelreich converted a CGE mount to OnStep using Arduino Mega2560 and RAMPS with LV8729. The post contains some amazing images taken with this mount and a 10" Newtonian OTA.
  • Bram Slagmolen converted an iOptron EQ45 mount using the MaxPCB, TMC2130, 400 step motors, and 2:1 reduction using pulleys. In the aforementioned link, there are details of how he built the controller, and detailed pictures of attaching the motors.
  • Richard Shagam converted an iOptron SmartStar PR EQ mount, and described his conversion in detail in this PDF writeup.
  • Jean-Francois Harvey converted a CGE mount to OnStep using the STM32 controller. In this thread he provides pictures of the converted mount and how he converted it. Also, with PEC recorded, he is able to do 300 second unguided exposures at 1371mm of focal length (AT6RC + flattner, with Canon T3i). He used NEMA 17 motors @ 1.68A, LV8729 drivers, and 1/64 microsteps for tracking and 1/16 microsteps when slewing.
  • Markus designed a mostly 3D printed kit for converting a Vixen GP-D2 mount to Teen Astro. Since this uses stepper motors the hardware part is directly usable with any OnStep controller. It could also fit other EQ5 type mounts.
  • User Aisling Lightworks was facing problems with his old Celestron CGE mount. He converted it to OnStep using the STM32 controller, NEMA 17 motors, and some custom mounting for the motors that accommodates pulleys and belts. The controller fits inside the mount base with a fan. See a brief video and pictures in this thread. Another extended video has much more info. Here is an example of M51 with 8 minute guided exposures, and a total of 3.5 hours of integration.
  • User simingx built a telescope based on the SHF 17-80-2SO Harmonic Drive, and a NEMA 17 with 30:1 high precision gearbox. Examples of the Veil Nebula, M8 the Lagoon Nebula and M20 Trifid Nebulas in this thread.
  • Gord Tulloch posted pictures of how he mounted the motors and pulleys on his CG5 mount.
  • MW Kuyper posted a list of links to the parts he used to convert a CG4 mount, including motors, pulleys, belts and couplers.
  • Saleh Ramadan converted a Celestron CG4 (EQ3-2) using 3D printed brackets, geared NEMA14 motors directly driving the worm gears, and the MaxPCB2.
  • Roman Hujer converted a Seben EQ3 mount to OnStep. He used custom etched copper boards for the RJ45 connectors, and 3D printed brackets.
  • Mihai Gavrilciuc converted a generic EQ5 style mount to OnStep. He used the STM32 PCB, with LV8729 drivers, NEMA 17 0.9 degree motors, and 4:1 pulleys and belts.
  • Francois Bouchard is in the process of converting a Celestron CGEM to OnStep. He used 0.9 degree/step motors, 4:1 pulleys and belts, and it shows a significant improvement in autoguiding.
  • Carsten Moos converted a Vixen Super Polaris to OnStep, using 3:1 pulleys and belts. Here is the overview, and here is are pictures of the detailed conversion. Another conversion of a Vixen Super Polaris was done, with pictures.
  • Bojan converted two EQ6 mounts to OnStep. His design is different in that it can be driven from OnStep, or the old Mel Bartels' system. To do this, he split the controller from the drivers. The drivers stay in the mount, with the stepper motors, and a connector can connect to either system.  
  • Rick Foust converted a massive 1960s GEM to OnStep using the MKS Gen-L all-in-one RAMPS board, and the S109 high current drivers. He has two focusers. The mount is able to carry a 16 inch Skywatcher Newtonian OTA, with a DSLR, focuser, autoguiding scope and camera. 
  • Keith Trivett converted a Meade LXD 75 (yet another EQ5 variant) to OnStep, using the STM32 Kit, 400 steps/rotation NEMA 17 motors, and FYSETC LV8729 drivers. The link has detailed photos of the conversion. Results from his first ever attempt at astrophotography can be seen here.
  • Eric Coustal converted a 30 year old Celestron CI700 to OnStep using a MaxPCB, with TMC2130. Detailed photos of the controller, the mount, as well as astrophotographs taken with it are in the link.
  • An amateur astronomer in Korea made a harmonic drive telescope using machined aluminum. He used CSF32-160 for RA and CSF20-80 for DE.
  • Gilles Gagnon converted an Astro-Physics AP400 mount to OnStep, using the MiniPCB board, and NEMA11 motors. He used 6160 aluminum to machine motor adapters. You can see pictures and info here.
  • Khalid Baheyeldin converted a Vixen SXD to STM32 OnStep. The manufacturer's servo motors were replaced by Oriental Motors Vexta NEMA11 motors with a built-in 18:1 gear head. This reduction ratio allows this relatively tiny motor to drive a relatively heavy mount. Holes were drilled for the screw to hold the motor. Pulleys were used to replace the manufacturer's spur gears. The pulleys are 1:1 16T each. A small perfboard was used inside the mount to replace the electronics. It connects the motor to two RJ45 sockets. These sockets connect using regular Ethernet cables to the OnStep box. The OnStep electronics uses the low cost STM32 PCB
  • Roman Michler converted an EQ5 mount using a MiniPCB, belt and pulleys, and a nice case. He shared a video detailing the manufacturing process.
  • Kenric Ma converted a Takahash NJP to OnStep using an Arduino Mega 2560 for the controller, with a custom sheild and DRV8825 drivers. ESP01 was used for WiFi, and a DS3231 RTC. The housings were 3D printed.
  • Guido Muesch made his own equatorial mount from scratch, machining an aluminum RA worm wheel. He used the MKS Gen-L board with TMC2100 drivers.
  • tnut55 converted an Exos1 mount using the MiniPCB. Pictures and description here.
  • Klaus Steinen built three OnStep controllers. One is a conversion of a Vixen GP for his brother, with TMC2130 in SPI Mode and drives NEMA17 1.8° Stepsize Motors, with max current per Coil of 0.75A. A switched regulator Module from Amazon is used.  Another system if for a Fornax 52 mount with NEMA 23, 0.9 degree/step, with max current of 1.7A per coil. The gear ratio is 10.8, so it is no problem with the max 1/128 microsteps. A third system is a Losmandy G8. See the pictures, more pictures, other pictures, and read the description, and more description.
  • w.xenon converted an EQ5 mount to OnStep, using RAMPS 1.4, WeMos D1 Mini, and a DS3231 RTC. Pictures show 3D printed mounting brackets and connectors for cables, here.
  • Prasad Agrahar converted his Vixen Great Polaris mount to use OnStep. You can see pictures of the mount, and two short videos in this blog post.
  • Instein.EU built a very professionally finished OnStep box for EQ5 mounts. It uses a small footprint Arduino Mega 2560 with a crystal oscillator, and flat Ethernet cables for connecting the motors, as well as aluminum brackets and casing. Links and Video to how he built it are listed in this message.
  • Pedro motorized an EQ5 mount (another picture) using OnStep and Howard's MiniPCB.
  • An OnStep user converted an Orion SkyView Pro mount to be powered by OnStep, and is capable of doing 10.9 degrees per second when slewing. A video of it is available here.
  • Gintautas built his own custom equatorial mount for a 10 inch Newtonian. He used OnStep with MaxPCB, and Teensy 3.6 to drive the mount. He used eBay TMC2130 drivers, modified to enable SPI functionality. He also added an RTC, and two focusers using DRV8825 drivers.
  • Chris Vaughn converted an EQ5 mount to work with belt driven NEMA 14 steppers with OnStep MiniPCB. Pictures of the mount, and images taken with it are here.
  • Raymond Collecutt built two mounts using OnStep. One is Takahashi NJP (originally a Temma2). With a belt drive, it has much nicer guiding on the DEC axis with OnStep, and 3X the slewing speeds. You can find pictures on Flickr.
  • Roman Hujer build two OnSteps for two mounts. The latest is a 3D printed Travel Scope powered by OnStep. Pictures and 3D printed parts for his first iteration are available at Thingiverse. Second iteration, with metal gears, are here.
  • Someone converted a Jinghua ET-8 EQ3 type mount to OnStep.
  • Matthew Abbey converted a 12.5 inch Newtonian to work with OnStep, using a custom made equatorial mount. Details here and here.
  • A project for converting an old CG-11 mount to Goto, using direct coupling of the motors to the worm gear. This way, he avoids Non-Periodic Error (NPE) from the gear reduction.
  • A video by Howard Dutton of his modified Losmandy G11 mount slewing using OnStep.
  • Kai Wicker modified a Vixen GPD2 mount to work with OnStep. His solution is a Teensy board, and RAPS128 stepper drivers.
  • Christoph Reinhardt, in German, (Google translation) modified a Vixen Super Polaris to work with OnStep. He provides detailed schematics on what he did. His version is AdruPilot Mega
  • An EQ5 mount using OnStep, controlled from a smart phone.
  • Another mount using OnStep and a tablet.
  • A video of a custom Equatorial mount using Onstep.

Dobsonian Telescopes

Although the original Dobsonian was a hand operated instrument, people have been motorizing their mounts for some time. With OnStep, a Dobsonian can be both motorized and computerized, providing Goto and object tracking as well.

  • User Butchf converted a Dobsonian to OnStep using the MaxPCB, and high resolution encoder (10,000 CPR = 40,000 PPR using Quadrature). You can see detailed pictures in this album.
  • Mihai Gavrilciuc converted a 12" Dobsonian telescope to OnStep using NEMA 17 motors. Pictures, videos and description can be found here.
  • Zeppy converted a 12 inch Orion XT12 Dobsonian from PushTo to Goto, using OnStep and the STM32 PCB, and DRV8825 drivers. He used NEMA 17 motors with an integrated 51:1 gear head, and a GT2 270 tooth pulley from Thingiverse, as well as a basic hand controller.  Here are detailed pictures on how he did it.
  • Tom rebuilt his 22 inch Dobsonian telescope, and added OnStep to make it track the sky and have Goto. A detailed write up of the rebuild is in this CloudyNights thread, with pictures.
  • Tony built a 13 inch truss Goto Dobsonian powered by OnStep. It is small enough to fit in a travel suitcase. Detailed pictures and a short video can be viewed here.
  • Pete Ingram (user rederickus on CloudyNight), converted a Dobsonian to use OnStep MiniPCB. The photos are on this CloudyNights thread , and the description is here.
  • Raymond Collecutt built two mounts using OnStep. One is a 20 inch Dobsonian,  You can find pictures on Flickr.

Alt-Az Mounts

There are some Alt-Az mounts that are not Dobsonian.

  • Keith Trivett converted a Vixen Porta II to OnStep using the STM32 and 400 step motors.
  • Mike Gore is in the process of converting a Meade LX200 fork mount to OnStep. Details and images here, here and here.
  • Miguel Gil converted two Alt-Az telescopes to OnStep. One is a fork mounted SCT using RAMPS, DRV8825, DS3234 RTC, and HC05 for Bluetooth. The other uses a Mega2560 with TB6600 high current stepper drivers, DS3234 RTC, and HC05 for Bluetooth. Pictures are provided in the previous link.
  • Pete Ingram converted a Vixen Porta II mount to use OnStep.

Controllers for Unspecified Mounts

The creators of these controllers did not specify a mount design.

  • Charles Lemaire built TeenAstro, a slim, professional looking build based on OnStep, with a hand controller. More pictures here, here and here of the hand controller. Videos links are here.
  • Serge Claus built an OnStep controller using simple off the shelf components, with no soldering. An Arduino Mega 2560, a RAMPS 1.5 board, a Wemos Mini Pro shield, an DS3231 RTC and TMC 2100 drivers.
  • Another OnStep Project

Hand Controllers

The OnStep Hand Controller use the ST4 connector to move the telescope. Useful for alignment. All of them have physical buttons for tactile feedback. For this reason the are can be used in the dark, if wearing gloves, and there is no need to look at a screen.

  • Dave Schwartz designed a low cost ESP32 based SHC, and Khalid Baheyeldin ported the SHC code to work on it. Here is a short video demonstrating it, and more info on it, including pictures, as well as links to the STL for a 3D printed case.
  • Gilles Gagnon made his own SHC, using an Teensy 3.2, a stripboard and a nice looking ready made case. Pictures and details of the internals and the finished SHC can be seen here and here.
  • Roman Hujer created a 3D printed case and tripod holder for the Teensy 3.2 SHC. Also, he has some variants of the PCBs for the SHC.
  • A Teensy 3.2 Smart Hand Controller (SHC) is available in Alpha (as of July 2018). It has a screen, and a menu to do most operation available from the Android App.
  • Pete Ingram created a simple hand controller, using a strip board, and off the shelf components. Pictures of its internals, and how it is wired here.
  • Roman Hujer created a hand controller for OnStep, via the ST4 autoguiding port. Here are the details of the design.
  • Charles Lemaire built TeenAstro, a slim, professional looking build based on OnStep, with a hand controller. More pictures here, here and here of the hand controller. Videos links are here.

Miscellaneous (Mounting Brackets, Cases, ...)