The so-called reed electric motor differs from the usual collector motor by the presence of only one electromagnet and one switching element. The direction of its rotation is determined at start-up and is subsequently maintained unchanged by inertia.
Disassemble a damaged electromagnetic relay with a tripping voltage of several volts and a tripping current of several tens of milliamperes. Carefully, so as not to tear off the leads, remove the electromagnet from it.
Take two permanent magnets and a cylinder of non-magnetic material. Glue the magnets to the cylinder so that they are exactly opposite each other. Outward, the magnets should have the same poles (either both north or both south). The adhesive should be chosen such that the magnets do not separate from the cylinder as they rotate. Wait until it dries completely.
Make for a cylinder or use off-the-shelf bearings of any design. Place it between these bearings so that it can rotate.
Take a two-anode zener diode with a stabilization voltage of about 25 V. If you do not have a two-anode zener diode, use two conventional ones with the same stabilization voltage. Connect them in series, anode to anode, and cathodes outward. Connect a two-anode zener diode or equivalent in parallel with the electromagnet.
Connect the electromagnet to a power source with the voltage for which it is designed and bring it to one of the magnets. Did he pull or push? If attracted, reverse the polarity of the electromagnet, if repelled, leave the polarity the same.
Now unplug the electromagnet from the power source and then plug it back in, this time not directly, but through a reed switch. Bring the electromagnet to the magnet on the cylinder on one side, and on the other, strictly opposite the first, bring the reed switch. Moreover, the axis of the electromagnet must be perpendicular to the axis of the cylinder, and the axis of the reed switch must be parallel. The engine will start to rotate.
Having chosen such a position of the electromagnet and reed switch, in which the engine works reliably. Secure them in this position using brackets made from available non-magnetic materials. Do not leave the running motor unattended.