1240 Focuser as driver for a JMI Motofocus
On 2007 I adapted a 1240 focuser to drive the JMI motofocus of my C8 Scope
As I stopped using the control panel of the DS motors once I got the LXD-75 mount, I dissasembled the panel and used it to create a focuser controller for multiple focuser motors.
When I'm doing Solar Astrophography it is imperative to have a motorized focuser for all your scopes, on my Solar Imaging setup I have three scopes:
A Williams Optics ZS 66SD
A Coronato PST (that uses two motors)
A ETX-125 OTA
So I needed a way of being able to control each motor without having to walk all the way to the Telescope and change the plug on the 1244 Control (see http://fdiazhome.tzo.com/Astronomy/Focuser1244)
Even when I have the skills to create a microcontroller for this, but didin't go that way for several reasons:
1 - Time to develop the software in assembler or any other languaje
2 - I don't have testing hardware, so I would have to work with the final product
3 - I would have to develop my own PC interface
As per Gene Nolan's suggestion I put my hand on a Vellemann Kit K8055 (that has a lot more funtions than the one I need for now) but it allows me controlling digital ports bit by bit, this in connection with a relay box, allowed me to create the controller.
Assembling the Kit was a matter of about two hours :-)
On this imageyou can see the controller board and the output connector, a ethernet type connector, this allows the ability of sending the signals for considerable large distances. (In this specific case I'm using a 6 foot cable)
The Relay Box
On the image above, you can see the relay board and sitting on top of it the Meade 1240 Focus controller and the connecting ports (4), if for some reason I don't want to use the relay box, I still can use the focuse controller by connecting the motor to the connector on the side, that bypasses all the relay circuitry.
Final setup in the mount tripod, you can see the three focuser motor cables and the green interconnection cable.
The Control Software
Vellemann offers a windows DLL that allows you to connect to the controllers using differnt software development packs, i used the Visual Basic templates and modified it so I can just control four bits of the controller 8 bit port, of course I could save some wires by enconding the outputs in binary code (using three bits) but using the four bits saved time and money by not having to build a decoder and put it on the relay box.
The final compiled version of the software setting on top of the Meade telescope control (Autostar Control) shows you how much control you have of the focusing and the telescope.
As you can see the small square allows me to control wich output will be active, I made an electrical interlock that gives priority to the lowest port, so if by exmaple you select 1 and 2, only 1 will be connected to the meade motor controller, on the bottom right of the Meade screen, you can see the focuser speed slider and focus in and out buttons, other controls like N-S or E-W appear on to of the simulated keyboard. Note this side of the
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