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A couple of friends and i want to build an orrery.

We are having trouble in figuring out what would be a good power source for our motor. We are planning to use one motor to run the central gear which will then run the other gears. Since the orrery is going to be constantly working, we need a constant power source. Suggestions?

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closed as unclear what you're asking by Elliot Alderson, Chris Stratton, Anindo Ghosh, Charles Cowie, Edgar Brown Jan 15 at 19:21

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    \$\begingroup\$ What's wrong with plugging it in to the wall? \$\endgroup\$ – The Photon Jan 6 at 18:36
  • \$\begingroup\$ The standard 220V is too high and would most likely burn out a small DC motor. We could get a rectifier but I presume that those are usually expensive. \$\endgroup\$ – jdoe Jan 6 at 18:45
  • \$\begingroup\$ D cells and a small unipolar stepper driven with FETs and a controller which does not keep the coils on between steps. It will be a lot easier if you're willing to let it stop for a couple of seconds while changing batteries, otherwise you can provide two battery packs with sharing via schottky diodes and change out one at a time. Chose everything for low quiescent current. Use a small barebones MCU running on a watch crystal and sleeping in between steps. There are fancier alternatives and more exotic battery types, but you should have more awareness before trying them. \$\endgroup\$ – Chris Stratton Jan 6 at 18:46
  • \$\begingroup\$ If you just use a geared DC motor, your speed will change as the battery runs down - okay for an "oh, pretty!" gadget but not if you intended to have any meaning vs. time. \$\endgroup\$ – Chris Stratton Jan 6 at 18:48
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    \$\begingroup\$ You have left too much information out of your question. Provide the specifications of the motor and quantify what you mean by "expensive". Do not put this information in the comments, edit your question to add it. We can not read your mind. \$\endgroup\$ – Elliot Alderson Jan 6 at 18:54