Redoing the power distribution of my scope

After many years of use, I’ve decided that it’s time to redo the power distribution of my telescope.  The power box project that I did was great at the time, however over the years there a couple of things about that project that didn’t really work out too well.  Here’s the problems that I had with the first version.

  • Power meter was never properly calibrated
  • Power meter circuit stopped working after a while
  • There was a switch for the telescope.  This was a waste of time, and a possible source of problems
  • The cable that ran from the box with the circuits, to the scope had bad plugs
  • There are 6 sockets for the dew heater, but I’ve only ever used one, and in reality, have no need for the others
  • The sockets that I put on the scope are pointing outwards, this has caused me to brake plugs a couple of times
  • The connector from the battery to the power box didn’t feel secure.

That’s quite a glitch list, so as I’m going to remake the power box, it’s time to take the opportunity to solve those problems.

The fuse board that I created worked extremely well. The bargraph that I had for the dew heater works well, but it’s using power that’s not really needed, might rethink that.


For powerbox version 2.  I’m keep the best bits and tweak the rest.



Starting with the box that will be connected to the scope, I’m going to change this almost completely.  Here’s the spec of the new version

  • 2* mono socket each supplying 12v from the dew heater. (one for the scope, and one for the guider scope if I make the heater)
  • 1* 2.5mm dc socket – 12v power for accessories
  • 1 * 2.5mm dc socket – 5v power for my SynGuider
  • 1 * power cable for the scope.
  • 9 way D-Sub socket


The D-Sub connector is the kind that is used on Serial ports.  9 way, allows for 4 pairs or wires to be used, The socket is rated for 7 Amps pin, so that’s plenty, as the Dew Heater is only capable of a theoretical 6 Amp.  The scope itself only needs 2 Amp.  The SynGuilder is only 200 mA at most.

The connectors will be mounted to the sides of a project box that I bought from Maplins.

Using a serial port, means that I can use pre made off the shelf cables. Not to mention that the plugs are much less flimy and should be less vulnerable than the round connectors that I used before, plus they can be locked into place, which is a bonus.

The scopes power will be from a cable that comes out of the box, via a rubber grommet.  This will mean that the scopes 2.5mm socket has no strain on it, and the connection is not likely come undone by mistake.  This worked well on the v1 power box, so I see no need to alter that part of the design.


The power distribution box

This time, I have a slight different problem that will need to be solved.  I need to supply the 5V power to the scope, box.  This will be done with one a dc/dc converter.  This thing is small, so will easily fit into the base box.  However, voltage drop might be an issue with this one, so I might try to put this unit into the box on the scope end if there is room.

The dew heater controller will be the same as before, Using a Vellman K8004 Kit I have two of these, they work extremely well and I have 0 issues with it.

This time, I’m thinking of either skipping the bargraph display, or changing it to use an LED package and light pipes, if I do it, it’ll be more work, but should mean a better build in the end.


The power box, will have a switch for the dew heater, I’ll decide later if this is going to be illuminated or not.  My current thinking is probably not.


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