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enter image description hereI'm currently trying to develop a circuit to eventually transfer to a pcb and I'm seriously stuck constructing it, this is my problem:

  • The circuit needs to rotate an 8 segment circle so that once a day the circuit will rotate into a new segment.
  • Then also once the circuit has run 8 times passing through all segments I want a button that will reset the program so that it will run the next 8 segments.
  • I want to also be able to develop this to be a pcb as I want to 3D print a case for the device hence I need it to be portable and battery powered.

PS I’ve had numerous people tell me that this task is simple but no one can develop a circuit with me.

edit: The picture I have described is shown below and I only want to create PCBs because I have a few animals that I use to feed them and handmade circuits just make the place look awful. So I want to create battery powered device. I’m a 3rd year electrical engineer but sadly they only teach us theory and not how to create things ourselves :(. I understand what I need to do im just more so asking what parts anyone would recommend im currently looking at using an A4988 and some micro controller with a crystal.

For more detail: the mass of the object that is being rotated is around 50g and im using this stepper motor: https://au.element14.com/nanotec/sp2575m0206-a/stepper-motor-7-5deg-1-6n-cm/dp/4743209

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    \$\begingroup\$ Why the reset button - it will automatically increment to the start position? What "motion" devices have you considered for rotation? \$\endgroup\$
    – Andy aka
    Aug 18, 2020 at 13:23
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    \$\begingroup\$ Can you draw diagram to show how the setup is supposed to look like ? Add the diagram into the question using the small edit button below your question. \$\endgroup\$
    – AJN
    Aug 18, 2020 at 14:13
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    \$\begingroup\$ Your question does not come close to adequately describing the thing that the motor is intended to turn. To select a motor, you must know the dimensions and mass of the structure, the orientation of motion with respect to the earth and the distribution of the mass. You must know the characteristics of the support system including friction. The motion is not completely described either. Do you need to rotate the structure 45 degrees in a certain time then wait a certain time before rotating another 45 degrees, or must you rotate the structure at a steady speed of 1 revolution every eight days? \$\endgroup\$
    – user80875
    Aug 18, 2020 at 14:14
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    \$\begingroup\$ Does "run the next 8 segments" mean that there is more than one structure being rotated or does it simply mean start another rotation? \$\endgroup\$
    – user80875
    Aug 18, 2020 at 14:18
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    \$\begingroup\$ I'm curious why you need to transfer to PCB? If you're only building one, there's nothing at all wrong with a hand-made circuit. If you're going "mass production" (i.e. you wanna sell these), you'll need a real EE to be involved much more than just some random questions on the internet. (Assuming you want a safe & reliable product) \$\endgroup\$
    – Kyle B
    Aug 18, 2020 at 14:19

1 Answer 1

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The requirement, in brief, is as follows:

  • A circular container is to rotate through 45°, once a day.

  • At the end of 8 days the top of the container is to be removed for refilling.

Here's how it could be accomplished:

  1. Any suitable battery-powered motor could be used.

  2. The mechanical interface between the motor and the container would be an 8-slot internal Geneva Mechanism, which could be fabricated to suit.

enter image description here

Image courtesy 'Mechnovashia'.

One revolution of the motor, linked through a single pin (shown in green) to the slotted plate (shown in orange), would rotate the latter through 45°.

The following animation very clearly shows the working of the mechanism.

https://www.youtube.com/watch?v=WekkYlHdJko

  1. A quartz clock based timer could be used to trigger a single rotation of the motor once in 24 hours.

The advantages of this scheme would be

  • No need for any special controller
  • No need for any programming
  • No need for a reset once in 8 days.
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