Motors and engines

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  Arduino tachometer with optical gauge

  I need a tachometer to calculate some mechanisms. For example, to calculate the speed of a robot vacuum cleaner, you need to know the rotation speed of the electric motor and, based on this, calculate the gear ratio of the gearbox.
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  Powerful homemade lawn mower for the village with their own hands

  I made this powerful lawnmower myself for the village, there is always a lot of high grass, which is not rational to fight with the usual manual trimmer. This animal mows down everything, tough grass, small trees, levels of hills, covered with moles, and even turns old bricks out of the ground.
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  How to connect a stepper motor to the driver, color coding of wires

  The eternal problem, which wire to connect :)