Building a Power Box for a Telescope

The more automated my setup has become, the more cables it requires and it has now got to a point where I want to simplify my set-up. The first element is therefore to build a future-proof power unit to mount on the scope and power my focuser, cameras and USB hub, all of which run off 12v. I also want to power my Canon DSLR, which runs at 8.2v, off the same unit. The whole system needs to be light enough to mount onto a scope and not affect the weight. I also need to design and 3D print a mounting system for each of my scope tubes.


  • Soldering iron and solder
  • Pliers
  • Drill and appropriate bits
  • Cable stripper and crimper


  • Weatherproof junction box (200mm x 120mm x 175mm)
  • Universal blade fuse 6 way box
  • GX16-2 Aviation 2 pin Connectors (5A rated)
  • Buck converter to step down voltage
  • 16 AWG wire
  • 12 AWG wire
  • 5.5mm x 2.1mm Male and female DC Power Plug and connectors
  • Heatshrink Electrical Sleeves
  • Electrical crimp connectors
  • 20A Bus bar power distribution


  • This involves a fair amount of soldering so knowing how to solder well and efficiently is an advantage. 
  • You also need patience – test everything twice before moving on. The whole project probably took me around 6 hours.


I mounted all the components I needed into the junction box using plastic spacers and superglue, ensuring that there was room for the wires and that I always had a clear idea of the flow of current through the circuits. The 12v input went straight into the 5A fuse box before running 5 outputs to the aviation 2 pin connectors. I opted to keep left positive (looking from the outside into the female connection) – and then ran the outputs of each of those connectors onto a bus bar before connecting back to the DC output (another aviation plug).

Components in place

The buck converter is on the right (with the heat sinks); the fuse box is on the left at the back (no blade fuses in yet). I added the full bus bar in at the end of the project (where all the negative cables are joined on a single bolt for testing).

The 6th output from the fuse box went into the buck converter to step down the voltage from 12v to 8.2v to match the Canon’s power requirements. It is worth spending a little money on this buck converter as you don’t want it fail! The output for the DSLR is a more simple 5.5mm x 2.1mm power plug.

At every stage, I tested the circuit using a multimeter to ensure that I wasn’t mixing up any polarity or pushing out too many volts. Only once everything was tested and re-tested did I make up the cable lengths I needed to connect to my 12v items. I used the 16 AWG wire for this as it will easily deal with any current – on one end I put a DC power plug, and on the other a male aviator plug that can screw into the connectors on the box.

Internal wiring

Here we have all the internal wiring complete, and ready for testing with the multimeter.

For the DSLR, I had an existing dummy battery from an AC/DC power unit that I simply cut and attached a DC power plug onto. I again re-tested this before putting into the camera for a test.

DSLR test

A successful test on the DSLR powering up!

I have 3D printed a mount for one of my scopes to allow me to attach it using velcro, and have also used velcro to attach my Moonlite focuser control, and a 7 way USB hub, to the outside of the box.

Each of the connections is fused at 5A to protect against surges – there are more fuses at the power end of my system for redundancy. The next step will be to connect up all items on my scope and run a full stress test, using a power meter, to see how much current is being drawn. I estimate even with the TEC cooling running to keep the camera -30c below ambient, the power box will draw less than 5 amps total. 


The completed circuits inside the box. The input connector is on the right hand side. The bus bar is now in place front left.


The finished box with a pen for scale

Currently I will power this via a cigarette-style 12v plug (as seen on the power cable). Eventually, and depending on the maximum amps drawn, I might remove that and connect to the 13.8v DC bench tester itself via a second buck converter (to reduce down to 11.8v). 

Once I finalise my mounting options, I’ll update with more images.


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M45 Pleiades – The Seven Sisters

The Pleiades are viewable in the winter skies in the Northern Hemisphere and appear as a cluster of brightish stars. When imaged through a scope, their nebulosity appears and you see them in all their glory. The M45 open star cluster is approximately 17 light years from Earth and are a relatively easy target for beginner astro-imagers. They are best known for their blue stars that illuminate what is regarded as an unconnected dust cloud between the cluster and Earth.

This image was shot on an astro-modded Canon 100D camera in early winter through a Skywatcher ED80 scope using a 0.85x focal reducer. The images were stacked in AstroPixelProcessor which is now my go-to software for stacking and pre-stretch package. I used darks, but no flats and the image had light pollution removed in APP before moving the stack across to PixInsight for final noise reduction and saturation.

The total integration was 40 x 240 seconds @ 800 ISO.

I really must get around to blogging a full review of the capabilities of APP – I can’t recommend it enough for stacking and light pollution removal.

I am really starting to view my DSLR as a solid imaging camera when I can’t be bothered with processing huge numbers of LRGB images on a mono camera setup


Higher resolution on Astrobin

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An evening with Prof. Brian Cox

A pretty amazing thing happened in Manchester last night; 12,000 people filled the MEN Arena on a Saturday night, not to see a band, but to watch a physicist talking about astrophysics, the origins of the universe and the likelihood of life on other worlds. And I was one of them!

I missed Brian Cox’s last tour and immediately kicked myself for not bothering to grab a ticket so, last February when a new tour came around, I immediately bought a couple of tickets and began to make plans. We booked the hotel pretty sharpish and then quietly forgot all about it until just after Christmas when we both realised that it was only weeks away.

And so it was we joined an army of other geeks, physicists, and the just plain curious in filling Manchester’s premier concert arena to watch Brian Cox play his home town. And boy did he not disappoint. The night was a strange blend of lecture, comedy and pathos that had me gripped for the two plus hours Brian and Robin Ince (his co-presenter on The Infinite Monkey Cage spoke. The show was slick in its presentation and effects however Cox cut through all that, his gently spoken delivery begging for attention and understanding. The content was delivered at all levels, satisfying the keen amateur right through to the astronomer and dabbler in astrophysics I like to think I am.

We left with our heads spinning with new ideas and concepts – how likely was it that there is life on other worlds (statistically very high) and how likely is it that this life will be complex and living in civilised (sadly, a lot less likely). The message that came across strongest for me was that, empirically, there is only one civilisation in the Universe and we are it. We are fragile and, if we are to survive, we need to cut through all the crap we see in the world today in terms of greed and selfishness, and start to think of our place in the universe as a whole. We may be the only civilisation the universe will ever produce and that makes us special. It also beholds us to protect what we have before we disappear quietly into the void.

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