By Simon Dawes
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Index
  
 
6" Newtonian
 
 
Pinhole Finder
  
 
Electric Focus
  
 
Astro Hub
 
 
Paper Instruments
  
 
 
 
 

WJO Data Hub :

My observatory used to have cables everywhere until I built the WJO Data Hub.

This piece of electronics connects to my PC using USB2 and has the following outputs:

1. WJO Filter wheel (under test)
2. WJO Focuser (not built yet)
3. WJO DSLR exposure controller (not shown)
4. CCD USB port
5. Guide scope serial port
6. Mount serial Port
7. 5v and 12v power outputs.

The Hub sits next to the telescope so rather than having seven cables trailing across my observatory floor I now have one (which is actually under the floor)

 

 

 

CAUTION:
Connecting anything to your CCD, webcam, DSLR, PC etc. has the potential to cause damage, I have little knowledge of electronics and offer these pages on the understanding that any projects based on them are at the readers risk I can take no responsibility if you break something!

 

 

 

 

The WJO Data Hub is made from electronic 'building blocks' so required little in the way of electronics knowledge.

 

Canon EOS 400D DSLR Exposure control

Exposure control is provided by using one of the two analogue outputs, this drives the MAX4427 driver chip which in turn drives a normally open relay (the other analogue output drives the other channel of the Max4427 to turn on/off the power to the CFW)

Shorting the pin and sleeve of the 2.5mm bulb socket on the DSLR starts the exposure, removing the short ends the exposure.

The circuit is built using strip board and fits inside an old 1.25" filter case.

Although I am using analogue outputs from the experiment board, I use them as if they were digital outputs, by applying a value of 255 for 'on' and 0 for 'off' the reason for this is to keep the digital outputs free for driving the CFW and the (yet to be made) focuser stepper motors which require 4 digital outputs to control the stepper sequence each..

 

 

 

Control is through Visual Basic Express.

The software allows...

  • o Single or multiple exposures
  • o Set exposures or user defined exposure
  • o user defined delay between exposures

WJO Filter Wheel

Under construction, the CFW is built, software written, hub electronics complete, I am just waiting to test it, I will then publish construction details here.