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Meade LX90/#909APM-LX200 Guiding Interface

Pour la version Francaise, Cliquez ici :o)
Here is my "cheap but good" guiding interface to make highest precision autoguiding with a webcam and a computer, using the Meade #909 APM CCD Port :o)

Using this interface will allow a LX90 (with optionnal #909 APM) or a LX200, to get really good long exposure pictures, without doing anything !!! ;o)

It should also be used with all system having a 'standard' CCD Guiding Port, like LX50 for example, or even SkySensor2000, but with a "special" version of this interface...
I will try to test this interface with a much as possible different user setup, and i will add to this webpage all the results and possible working version :o)

This interface is actually handled by the :
Steve Barkes "GuideDog" software
And :
Axel Canicio "Astrosnap Pro" software
And Now
"K3CCDTools" from Peter Katreniak !!!

You must of course select the "Guiding/parallel", or "Bonduelle" interface in the guiding parameters window, and read carefully the instructions of those softs to start good autoguiding with your telescope :o)

WARNING !!! i'm not responsible for any damage to your APM, Scope or Computer, if you are not sure of doing this interface and cables correctly !!!

Here is the "Open Prototype" of the interface....
Not a lot beautiful, but fully functionnal !!! ;o)

I wanted to do that, to use the Meade CCD port who is working at about 2/3 sideral speed in corrections, possibly simultaneously in two directions :o)

It can be connected on the same // port as a VP-SC, ready to autoguiding AND long exposure imaging with the extended Steve Chambers Mod 2 using "GuideDog" or "Astrosnap Pro" !!!
(but it can of course be used with any webcam, modded or not, if pins 6,7,8 and 9 of a // port are free to be used !!!)

The low energy used by this interface shoud give us a very long time of guiding with a 9 volts battery, but i also realised a:
SPECIFIC version for the LX-90 with a MODDED #909APM
(you can go to the above link to see the shematics and the #909APM mod if you have a LX-90, and then return on this webpage to see the parallele port wireing and the use of this interface...)

With the component size of this interface, it should be also possible (but not tested) to place it inside a VP-SC, using the +5volt USB to power it, and use a cable connexion to the CCD port directly from the VP-SC !!!
(in this case, the le cable from the VP-SC to the // port should have 8 connectors and a ground)

The Meade CCD port is ignoring commands such as East AND West simultaneously, so that there is no risk from short circuit if an error occures in the CCD E,S,N,W connections... ;o)

I have add a LED to verify the good powering of the interface, and a "on/off guiding" switch to prevent simultaneously E,S,N,W commands while the guiding soft is not activated

Now, let's get a look to the shematics of the standard 9volt battery powered interface :

Here are the "special" components of the interface...
From left to right:
8x10Ko resistors train, ic4066B, ic78L05 and RJ12 connector for APM

Also needed :
8 resistors 470 Ohms
1 resistor 1 Ko Ohms
1 red LED (3mm diameter)
1 on/off switch
a 6 wires phone type cable to go to the CCD port
a 4 wires + ground type cable to go to the // port
1 // connector

Parallel port connections :
GuideDog and Astrosnap version :

To use the interface with a Steve Chambers modified webcam (VP-Sc or Tuc-SC), and with "GuideDog" or "Astrosnap" soft within the same parallel connector, you must wire up the interface as described on the electronic concept drawing
I mean :
Ground of the interface to pin 21 of the // port connector
East to pin 6
West to pin 7
North to pin 8
South to pin 9

(pins 2 to 5 are reserved for the Steve Chambers long exposure webcam mods)

Finally !!! :o)

You should power on the interface (or the telescope) BEFORE to power on the computer (or before to plug in the // port connector) for the ic4066B to be powered when the +5volts signals from // port arrives...
You should also put the guiding switch to ON, only when the soft is ready to guide, to prevent bad // port signals from other softs to do wrong corrections on the telescope !!!

If the telescope goes quickly away of the star, just put the guiding switch to OFF (the telescope will then stop to go out), and test other parameters in the guiding soft, or verify all the connections... ;o)

I want to say "Thank You" to Jean-Pierre Bourgeay for the help given in the development of this project, and to Axel Canicio for the beta-test guiding version of his fabulous "Astrosnap" soft :o)))
Also Thank You to the authors of the good describing Meade CCD port web pages, the starting point of this interface, and to Steve Barkes who had the good idea to also send the good guiding orders to the // port for my little guiding interface ;o)

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