Solar Motor Spinner With Easy Change and Adjustment of Magnets

Here is how to make a solar motor that is easy to adjust without glueing the magnets. And easy to try different magnets. Magnets stick themselves to an iron holder. I think the iron holder also boosts the magnetic filed strength.

I have recently become hypnotized by small solar motor toys that commute themselves:

https://youtube.com/shorts/vDAIM7nvXgs

A coil is soldered to a solar panel and tries to turn to align itself with the magnetic field of the magnet. But when it has turned, the second solar panel gets light and it is soldered in opposite polarity to the coil, so the coil tries to turn around further. So the solar panels are soldered togather anti-parallel (other description would be that panels are soldered in series and shorted). These motors unfortunately do not self start and need a slight push. Optimally the light shines from the 90 angle in respect to the motor magnet field axis.

Vertical round rotor balancing is not too critical, because it is round and compact some oscillations sideways do not kick it off.

Supplies from Aliexpress:

Wholesale 1pc 5pcs 10pcs Mini 0.5V 140mA Round Solar Panel 33mm Diameter DIY Epoxy Board Solar Cells Photovoltaic Panels Module 0,44€ FlyEnergyPower seller on Aliexpress. Round ones look nice and shake less. Can use also rectangular, also more than 0.5V.

Sewing Machine Plastic Bobbins

Magnet wire around 0.2 mm. Wind full bobbin.100-300 turns, maybe have not counted.

Hot melt glue, superglue, soldering iron, forceps, plyerrs, sandpaper, knife, tape...

Some iron small nail, or a sharpened bycicle spoke piece, sewing needle or knitting needle.

Iron sheet and saw. Or a metal ruler. Some bending edge to make 90 degrees bends.

Magnets experiment with any 8-25 mm.

Solar cells are 0.5V, ca 100 mA peak current. So the winding resistance to get the maximum power out would be R=0.5V/0.1A= 5 Ohm. My bobbins are about 10 Ohm. I use magnet wire 0.2 mm diameter, but guess 0.15-0.3 should be fine.

Sewing machine bobbins are very practical to use as they can be wound using a motor. They are 20 mm in diameter.

Magnetic force is proportional to the winding area, so probably larger diameter would be better to spin at dimmer light.

Spool can also be glued from cardboard. Or another alternative is to take some round insulating piece and glue it in -between the solar panels.

I use superglue to glue the things together, and hot glue to encapsulate the rotor against external shocks. also glued the nail with hot glue. Probably it if it will melt in hot summer sun.

Axis can be a short nail fixed with hot glue. Sewing needle would need stronger magnets.

Support is a single piece strip bent from iron material. Such strip can be cut out of an old Desktop PC case cover. Strip width is not critical about 25...30 mm. Metal thickness about 1...1.5 mm.

Or it is easier is to use a metal ruler yard stick that can be bent.

About 21 cm long metal strip is needed.

Center portion 8 cm height

bottom 9 cm

top ca 4 cm

I am lucky to have sheet metal bender so can bend 90 degrees nicely.

Idea to paint metal was not good, as paint is easily scratched by the magnets. Best was to put a 5 cm wide isolation tape around, or a sticky film. Plastic also absorbs shocks by the magnets.

Magnetic support at the top provides small friction when magnetic field attraction is almost compensated by the gravity. Small contact area also provides small friction. One can even put a steel bearing ball in-between the rotor and magnet. Such steel ball concentrates the magnetic field and provides less friction area. Friction can be further reduced if a piece of gorilla glass from a broken phone screen is glued to the magnet.

Try out different lights: sunlight, LED, incandescent.

You can put different magnets, see what works better.

Try to suspend the rotor on a steel bearing ball or even a chain of balls. They concentrate magnetic field lines.

Or try to get less friction by gluing a piece of thin glass to the magnet (e.g. hard gorilla glas from a broken phone screen). May be teflon layer would be better?

Have fun spinning!