Mains Power for Skywatcher Motor Focuser

Now I have the motor focuser on the 127 Mak I decided it might be useful to be able to power it from the mains when the opportunity arose. I had a rummage around for a suitable power connector socket, a spare PP3 battery connector (I planned to replace the original because the wires were short making it a pain to fit new batteries) and a few bits of wire.

Here’s how it looked when I started, and after removing the four screws from the back and taking out the circuit board:

At the top left of the circuit board there was plenty of space for the back of the socket, so I cut an 11mm diameter hole next to it in the side of the box. It was a very tight fit. In retrospect using a smaller diameter socket would have been a better choice:

Here’s the other reason a smaller socket would have been better. I had to cut off part of the rear flange so the socket would fit against the wall of the box:

Originally I was planning to unsolder the old battery connector from the circuit board but there’s a huge blob of glue over the solder points, so I trimmed the wires short and soldered the new wires onto them instead. Here’s everything soldered up. The power socket has three terminals. One is the pin (positive in this case), one is the outside of the plug and the third is connected to the second when a plug is not inserted. The negative battery connector is soldered to that third terminal and routes back to the original negative connection on the circuit board. The positive battery connection and the pin connection on the socket are both soldered to the original positive connection. I could have done that on the pin connector itself, but there were enough cables running about a confined area as it was. All the joints were shrink-wrapped:

Finally everything was reassembled:

Testing with a battery and 9V wall-wart worked perfectly.

This entry was posted in Astro Equipment, Astronomy, Projects and tagged . Bookmark the permalink.

3 Responses to Mains Power for Skywatcher Motor Focuser

  1. alec says:

    Hi James

    I know this thread was some time ago, but hope you are still there!

    If I refit my focuser as per your advice, can I supply it from a 12v battery with no ill effects?



    • james says:

      It’s only 9V, not 12V, but other than that I don’t see why it shouldn’t work.


    • Steve says:

      I use 12v, for the motor anyway. I have blown up the old handset and maybe that is why, but I made a replacement very easily out of a PWM controller off eBay.

Leave a Reply

Your email address will not be published. Required fields are marked *