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Depending on availability from the suppliers. Please contact us for more information

1'399.0 CHF tax incl.

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Designed to attach to popularly available equatorial mounts, the Telescope Drive Master™ (TDM) uses a mount-specific adapter, an ultra-high resolution encoder, and an electronics package that transforms your drive system into a super-performance, research-grade drive. This device does not require tedious PEC training, just turning on the TDM almost eliminates all of the periodic and non-periodic tracking error of your equatorial mount. 

The electronic controller unit compares the signals incoming from the high precision rotary encoder mounted onto the RA shaft with the time signal of its quartz oscillator. Any deviations of the angular velocity of the RA shaft from the prescribed drive rate, are compensated by feedback regulation in real time by accelerating or slowing down the drive. 

If further correction is needed because of errors other than periodic drive error, the TDM allows auto-guider input as well. 

This device consists of two main parts

  • A high precision rotary encoder mounted subsequently onto the RA shaft directly without any detachable clutch or gear, and
  • An electronic control box.

Principles of operation 

The electronic controller unit compares the signals incoming from the high precision rotary encoder mounted onto the RA shaft with time signal of the internal quartz oscillator. If the angular velocity of the RA shaft deviates from the prescribed (sidereal or average King-rate) velocity value, it accelerates or delays telescope’s driving clock. In this way, a high precision, feedback regulated, real-time rotational speed control has been created. Corrective action happens via auto-guider input port of telescope’s driver unit of its own. 

Advantages of using TDM

  • Eliminates telescope mounts’ tracking error down to negligibly small values. The followed object (without large scale proper motion) deviates from its theoretical position on the CCD surface in smaller degree than ±0.5” (or less than 1” p-v amplitude) during 5-10 minutes long observation more than in 95% of duration of total exposure time. (The data above depends on the object position observed in the sky, type of certain mount and accuracy of its polar alignment.)
  • It is not necessary to install auto-guider telescope or to use guider chip/camera.
  • It does not need to find bright guide star for tracking (the observation process can be automated on much easier way).
  • TDM can speed up the high volume observation work on remarkable way since exposition can be started immediately after the scope turned onto its target (and potential RA-gear backlash worked off).
  • High density filters (e.g. H-alpha) do not have any influence to the performance of tracking.
  • TDM is very easy to use due to its self-test functions.
  • TDM compensates each element of tracking errors coming from the whole RA drive chain (between motor shaft and RA shaft) since the rotational sensor has been mounted onto the RA shaft directly. It means that TDM inspects very slow rotation of RA shaft continuously in real-time and will correct it immediately if it is necessary.
  • TDM is a standalone application so it does not need any PC support or other external device for using it.
  • Thanks for the built in, high stability and high precision quartz-oscillator based clock-signal the tracking accuracy of the telescope’s drive system is not a relevant parameter.
  • The electronic module of TDM can be used for other mounts as well so you need to change the mechanical adaptor only if you have several mounts or want to change the type of your permanent mount.
  • Although TDM was developed as stand alone application up to 5-10 minutes exposure time, TDM v2.0 and higher versions support Auto-guider controlled tracking for longer exposures as well. It means you do not need to hunt for bright guide stars for your guider CCD chip and you do not need to have extra sensitive autoguider CCD because TDM will keep the mount on the right tracking speed with the highest practical accuracy between two auto-guider corrections. So you can use 10 magnitudes or dimmer stars for guiding with 10, 20 30 seconds (or longer) CCD integration time in the small size off-axis guider FOV: actually, you will be able to use ANY stars in your FOV for guiding.
  • It is possible to create a high precision periodic error (PE) curve of your mount using the serial (USART) port of TDM connected to your PC in your room without “in-situ” test under the night sky. You just need to download and use the software (TDM Monitor.exe) from the companion CD or from our website www.telescopedrivemaster.com.
  • TDM has been developed as “easy-to-use” device, so you can subsequently attach its mechanical adopter onto the RA shaft of most popular mass-produced telescope mechanics easily, without disassembling mount. This is a “Plug-and-Play” device so you do not need any special mechanical or electronic study or background to install and use it.

Always an extra telescope mount adapter kit need to be purchased. 


  • TDM electronic control box
  • High precision rotary encoder
  • Cabel kit
  • Power supply

Warning the kit does not include the encoder support for your mount.
Several supports are available on the site, choose the one for your mount