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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.


Skywatcher EQ5, Celestron CG5 Vixen SP/GP

Various 3D printed parts to attach the motor to your mount can be seen below on the individual conversions, or in the pictures and attachments in this thread.

  • User Egge converted a Sky-Watcher EQ5 mount to OnStep using the Blue Pill PCB. He used TMC2130 drivers with NEMA 17 0.9 degree 1.68A motors, 40T to 16T pulleys with belts, and a 3D printed case. Power is provided by a 19V laptop power supply.
  • Prabir Biswas converted his non-GOTO Sky-Watcher EQ5 mount to OnStep using the MKS Gen-L V2.1, NEMA17 1.68A motors, 40T to 16T pulleys.
  • Raphael Barbera Cordoba converted his Sky-Watcher EQ5 mount to OnStep using the WeMos ESP32 board with the CNC V3 shield. He used  LV8729 drivers at 1/32 microsteps. He added a 5V regulator. The mechanical components are 15T:60T pulleys and belts, and 3D printed adapters to attach the generic metal angled support from AliExpress.
  • Alex converted an EQ5 mount to OnStep using the STM32 Blue Pill controller, 60T to 15T (4:1) pulleys, and RJ45 Ethernet cables. He wrote quite a detailed article, with many pictures, on how he did it, as well as sample images.
  • Frederic Petronijevic used the MaxESP3 PCB to convert an NEQ5 mount to OnStep. He used Roman Hujer's 3D printed brackets for attaching the NEMA 17 0.9degree 0.9A motors, with TMC2130, and 40T/16T pulleys. This detailed thread how he went about doing this.
  • 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.
  • Sebastian converted a SkyWatcher EQ5 to OnStep using the MKS Gen-L board. The details of the parts he used are in the linked message. See his image of the Omega Centauri cluster.
  • Richard Shagam converted an Orion Astroview light equatorial mount to OnStep. He used 0.9 degree NEMA 17 stepper and 40T to 16T pulleys with a 160T belt for a 2.5:1 reduction. The mount is driven by a STM32 Blue Pill kit.
  • Roman Hujer converted an EQ5 mount to Onstep using the STM32 kit, and 3D printed parts.
  • Pete Ingram converted an EQ5 mount using 400 step motors, and 60T to 20T pulleys (3:1 reduction). See the link for detailed photos on how the motors and pulleys were attached.
  • Jean-Paul Nombret built a custom friction drive using 3D printed parts, and other reused parts. It uses OnStep on an Arduino Mega2560, driving Vexta 5-Phase 0.72 degree / 500 step motors from an old photocopier.
  • Corey Mooney converted a Vixen Super Polaris bought at a flea market to OnStep, using a Teensy on a Perfboard. Sample images he took with it using a 4.5" F/4 Newtonian and an 8" F/4 Newtonian.
  • 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.
  • 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.
  • 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.
  • Gord Tulloch posted pictures of how he mounted the motors and pulleys on his CG5 mount.
  • 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.
  • 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.
  • 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.
  • Pedro motorized an EQ5 mount (another picture) using OnStep and Howard's MiniPCB.
  • 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.
  • Roman Michler converted an EQ5 mount using a MiniPCB, belt and pulleys, and a nice case. He shared a video detailing the manufacturing process.
  • 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.  See the pictures, more pictures, other pictures, and read the description, and more description.
  • Lloyd Simons converted a Vixen Super Polaris mount to OnStep using the Wemos R32 with the CNC V3 shield. The motors are the 0.9A 400 step NEMA17 steppers, 48T to 16T pulleys for a 3:1 GR1 ratio, and LV8729 drivers. Also a focuser. You can see a photo of the entire setup, as well as a sample image here.

EQ6 Mount

  • Jamie Flinn converted a Rowan modded EQ6 mount to OnStep using an MKS Gen-L v1, a WeMos D1 with an antenna. The mounts uses TMC2130 SPI drivers, NEMA 17 200 step motors, 1/64 microsteps for tracking, pulley and belt reduction of 47/12 (3.916667:1), and 180:1 worm wheel.
  • 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. 

Skywatcher EQ3-2, Celestron CG4

  • User dtanon converted an EQ3 mount to OnStep using the R32+CNCv3 board with 3D printed motor brackets. His post includes detailed pictures of how he did this, as well as links to the parts and prices in Euro.
  • Alain Kinlough converted an EQ3-2 mount to OnStep using a custom PCB based on the MaxESP2, but removing the focusers. It is intended for visual usage, for now.
  • Roman Hujer converted a GSO GS-280 mount to OnStep, using the STM32 Blue Pill kit, JKM NEMA17 42BYGHW609 1.8 Degree Stepper Motor, with belts and pulleys.
  • Graeme converted an Orion EQ3-2 mount to OnStep. He used 0.9A 400 step/0.9degree motors, the STM32 Blue Pill kit, and LV8729. The link provides details on where he bought the pulleys belts, and mounting brackets.
  • 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.
  • 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.
  • Hanif Nanda converted a Seben EQ3 mount to OnStep using the ESP32 R32 with the CNC V3 shield.
  • Roman Hujer converted a Seben EQ3 mount to OnStep. He used custom etched copper boards for the RJ45 connectors, and 3D printed brackets.
  • A video of Roman Hujer's Seben EQ3 mount using OnStep and a tablet.
  • Someone converted a Jinghua ET-8 EQ3 type mount to OnStep.

Orion SkyView, Bresser Exos1

  • 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. It has a 2:1 pulley reduction, NEMA17 0.9 degree motors and 24V for power supply. A video of it is available here.
  • tnut55 converted an Exos1 mount using the MiniPCB. Pictures and description here.

Celestron CGE Pro

  • Eric Remy converted a CGE Pro to OnStep using the STM32 Blue Pill controller. The thread has details on how the mechanical and electornic parts are put together.
  • Curly converted his CGE Pro to OnStep. He used the MiniPCB2 with a Teensy 4.0, NEMA17 17HM19-2004S 2A 400 step motors with 12T-60T pulleys and 158mm GT2 belts giving 5-1 reduction, and custom machined motor mounts. The resulting images are superb, with acceptable unguided 5 minutes exposures.
  • Christan Kampf converted a CGE Pro mount  to OnStep. He used Quimat 200 step 1.7A motors, with 0.59Nm/84oz.in 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.

Celestron CGE

  • 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.
  • Marko Himelreich converted a CGE mount to OnStep using Arduino Mega2560 and RAMPS with LV8729. He used 5:1 precision geared planetary NEMA17 motors. with additional 48T to 30T reduction (8:1 for GR2). The post contains some amazing images taken with this mount and a 10" Newtonian OTA. More stunning images in his followup post.
  • 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.

Celestron CGEM

  • Chris Vaughan converted a Celestron CGEM using belts and 48:15 pulleys, MiniPCB v1, and TMC2209 drivers. Autoguiding RMS is better than before the OnStep conversion.
  • Francois Bouchard converted a Celestron CGEM to OnStep. Final pictures of the mount are here. He used 0.9 degree/step motors, 4:1 pulleys and belts, and it shows a significant improvement in autoguiding.
  • Patrick Kastelijns converted a Celestron CGEM for his friend, after its OEM controller board was non-functional. The cost of the parts was €100.

Losmandy G11 and Celestron CI700

  • Andrea Tasselli converted a Celestron CI700 mount to OnStep using the Blue Pill with LV8729 driving motors that have 1:8 integrated spur-gear gearbox, since those were already on the mount. He plans to replace them by 400 step motors and pulleys with belts. 
  • Jamie Flinn converted a Losmandy G11 mount to OnStep using MKS Gen-L V2, NEMA 17 1.68A motors, and TMC2130 drivers. This conversion using  The mount is used with a C14 SCT OTA. Photos and description here.
  • Rockmover cut aluminum sheets to make mounting plates, and then used 3:1 pulleys to convert his Losmandy G11 using the "reverse worm" method. See the picture here, and videos here. He had to remove the altitude knob though. The end result can be seen here. A video of the finished mount 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.
  • A video by Howard Dutton of his modified Losmandy G11 mount slewing using OnStep. Howard later changed the motors (Oriental Motors Vexta PKP246MD15) with TMC2130, and used bellows couplings to directly drive the motors. The results are in this video with the slewing speed much increased, and autoguiding much improved.
  • Corrado Gamberoni converted his Losmandy G11 mount slewing using OnStep. He used a MiniPCB2 with TMC5160, and pulleys/belt for 4:1 reduction to the motors. Here is a video, and pictures.
  • 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.

Losmandy GM8

  • Klaus Steinen converted a Losmandy GM8. See the pictures, more pictures, other pictures, and read the description, and more description.
  • JoAnn converted a single axis (RA only) Losmandy GM8 to OnStep, as a sky tracker. It does not have gears on the DEC axis, and that is why she uses it track the Sun, You can see images here, and read about it in this thread.
  • Guilherme Vênere converted a Losmandy GM8 to OnStep using 400 step NEMA 17 motors directly coupled to the worm gear.

iOptron Mounts

  • 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.

Takahashi

  • 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.
  • 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.

Other Brands/Models

  • 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.
  • 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. 
  • 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
  • Klaus Steinen converted 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. See the pictures, more pictures, other pictures, and read the description, and more description.

Custom Mounts

  • Othmar Ehrhardt converted a Meade LXD600 GEM to OnStep using a custom made board based on the MaxPCB, NEMA14 motors, and TMC2130. With PEC, he can get decent unguided 180 second images.
  • User tnut55 made his own custom equatorial mount. He used a MaxPCB v1.13 with RTC and Wemos D1 daughter boards, and 400 step motors with TMC2130 drivers
  • User Ulysse created his own custom equatorial mount around threaded rods and locking nuts and 3D printed parts. He used 400 step motors and 100:1 gearboxes, and 4:1 pulley and belt reduction. Details of the design are on Github and Thingiverse.
  • 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.
  • Carl Monfils create an equatorial mount from the ground up! Even the worm gears and worm wheels are custom made by him. He used an MKS Gen-L V2.0 with 0.9 degree 1.68A motors with LV8729 drivers and 60T to 20T pulleys for a 3:1 reduction.
  • An amateur astronomer in Korea made a harmonic drive telescope using machined aluminum. He used CSF32-160 for RA and CSF20-80 for DE.
  • 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.
  • 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.
  • Matthew Abbey converted a 12.5 inch Newtonian to work with OnStep, using a custom made equatorial mount. Details here and here.
  • A video of a custom Equatorial mount using Onstep.
  • 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.

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.

  • Jesse Lichtenberg made his own custom Dobsonian mount from readily available extruded aluminum and 3D printed parts. He used 200 step motors with integrated 100:1 gearboxes, an MKS Gen-L v 2.0 board and TMC2130.
  • When mil-cha's Skywatcher Stargate 500 20 inch Dobsonian's SynScan electronics died, he converted it to OnStep using a MaxESP3 PCB, and TMC5160 drivers. The results is that it is more accurate and quieter than the manufacturer's original electronics.
  • ProsperGuy converted an Orion XT10 Plus Dobsonian to OnStep using 3D printed parts. Details in this Thingiverse post.
  • John K. converted a Dobsonian telescope to OnStep using an MKS Gen-L board with S109 drivers, and NEMA 17 motors with 100:1 integrated gear reduction. He used custom designed 3D printed parts and pulleys. Total cost of the conversion was ~ US $215.
  • 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 22.4 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. The electronics use the new TMC5160 drivers, successfully, with 3.5 degrees/second slewing speeds. See this video of it slewing.
  • 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.

  • Bert Kruger converted a Celestron NexStar 11"Alt-Az mount to OnStep using the STM32 Blue Pill controller. He cut the fork to make it a single arm, and uses a C9.25 optical tube on it.
  • Kevin Ma converted a 1985 Meade LX-3 2120 fork mount to OnStep.
  • 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.
  • Keith Trivett converted a Vixen Porta II to OnStep using the STM32 and 400 step motors.
  • Pete Ingram converted a Vixen Porta II mount to use OnStep.
  • Jordi Sese shared information on his EQ5 mount that was converted to Alt-Az, and runs OnStep on a Mega 2560/RAMPS controller, with a 3D printed field rotator/derotator

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. The FreeCAD source file and STL's for each of the parts are also here in the files area.
  • 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, ...)