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I built a pier to accommodate my telescope and gear. I have 110V power available at the base of the pier. Currently I am using two different power bricks, one to supply 24V DC for the mount, and a 12V DC for the accessories, like mini computer and cameras. My biggest problem is the jumble of wires and power bricks lying on the ground that create a hazard when working near the pier.

I am wishing to install a cleaner solution. My needs are: one 24V DC power source that can provide about 6 amps to operate the telescope mount, and at least two 12V DC power outlets (I want to use Anderson Power-Pole connectors) that will feed the computer and other accessories mounted at the telescope.The total 12V draw is less than 10 amps.

What is the most efficient way to accomplish this? Can I use a 24 V power supply wired to the 110V AC input which will feed the mount motors, and then step down to a 12V bus bar that I can access for the accessories, or maybe a 12V power supply and a step up to 24V? Maybe there is another solution. My ultimate goal is a clean installation in one box hung on the pier itself (I can 3D print an appropriate box) with one input from my house 110 feed. Then I can have three Anderson Power-Pole connectors on top of that box, one for 24V and two for 12V. That would eliminate wires and power bricks lying on the ground and make a neat package.

Any thoughts are appreciated.

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  • \$\begingroup\$ how do you get a jumble of wires and power bricks lying on the ground with only two power bricks? ... and why didn't you plan for this when building the pier? \$\endgroup\$
    – jsotola
    Commented Dec 16, 2023 at 15:51
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    \$\begingroup\$ Why not just run 110 VAC from your house into the 3d-printed box (i suggest getting a properly rated enclosure though, if this is near water--you mention a pier), and then put the two power bricks you're using right now into that box? That seems easier to me, and it wouldn't cost you as much since you already have the power supplies. \$\endgroup\$
    – Hearth
    Commented Dec 16, 2023 at 16:31
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    \$\begingroup\$ Definitely agreeing with Hearth: 3D printing, especially of the common FDM variant, really isn't the method of choice here: you get boxes made for this purpose at relatively low cost, with at least rainproof gaskets and lids, that can take a beating once in a while. This is going to be mounted close to water – so you'll want at least IP66, if during heavy weather this might actually be submerged even IP67 or IP68, in protection class. (the first digit actually isn't as important to you, but the second digit tells you this is safe against rain, a water hose, temporary or full submersion) \$\endgroup\$ Commented Dec 16, 2023 at 16:40
  • \$\begingroup\$ Here's a list of boxes that might come into question. \$\endgroup\$ Commented Dec 16, 2023 at 16:49
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    \$\begingroup\$ @MarcusMüller I still recommend a decently high number in the first digit, since anything outdoors is susceptible to getting dirt and grime on it--though I'm not really sure if it's possible to make an IP07 or IP08 enclosure, come to think of it. \$\endgroup\$
    – Hearth
    Commented Dec 16, 2023 at 17:04

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If you are talking about purchased supplies, your total cost will be lower if there is only one off-line supply. One large 24 V supply, with part of its output down-converted to 12 V with one or more non-isolated DC/DC buck converters.

Power-wise, this is less efficient than two offline supplies, but it might be smaller, cheaper, or both. No matter what the datasheets say, assume no more than 75% efficiency for each converter, and size them so they are not running at more than 75% of their rated outputs. Margin = reliability.

If you have time, money, and are looking for a science fair project, check out high-density DC/DC converters.

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  • \$\begingroup\$ Thank you for your suggestions. I was thinking about one large 24v and down-converting to supply the 12v. I thought I read somewhere that a 12v can be stepped up efficiently also \$\endgroup\$
    – Sunpilot
    Commented Dec 16, 2023 at 17:22
  • \$\begingroup\$ In round numbers, partly because of physics and partly because of product evolution, boost converters are almost always less efficient than buck converters. That being said, the latest generation of switching controllers from Linear Technology and others boast over 90% efficiencies in both directions. But efficiency is expensive - more complex controller, bigger/fatter MOSFETs, etc. \$\endgroup\$
    – AnalogKid
    Commented Dec 16, 2023 at 18:42

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