pulse motor - bedini motor

thingiverse

I built this Bedini/Pulse motor because I was dissatisfied with other builds that were too complicated or not adjustable enough according to the parts I had on hand. The wheel uses 4 neodymium magnets, each measuring 5mmx3mm. All the magnets should have the same polarity facing outwards, meaning all south poles face outwards. https://www.aliexpress.com/item/32949700971.html?spm=a2g0o.productlist.0.0.6dee1a61rw6wKK&s=p&ad_pvid=202004190323283128102692848720003632215_1&algo_pvid=2cceb888-b404-47d8-a2c4-f5dd20256d39&algo_expid=2cceb888-b404-47d8-a2c4-f5dd20256d39-0&btsid=0be3746c15872918087232946e6e63&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_ As a shaft, I used a 70mm stainless steel needle for leather sewing. I purchased mine on AliExpress at: https://www.aliexpress.com/item/32960765733.html?spm=a2g0s.9042311.0.0.27424c4dvx8IZv Insert the needle into the rotor from the eye and press it down gently until it stops about 10mm from the point. The gantry is made up of two parts held together by a 3mm screw. To keep the needle point in place, use a 5mmx3mm or 5mmx2mm magnet on the bottom part of the gantry. On top, there's space for a 12mmx2mm magnet or you can stack three 5mmx3mm magnets and keep them in place with glue or double-sided tape. Don't use perforated magnets as they will cause the rotor to wobble. Adjust the height of the gantry to keep the spinning wheel vertical, with only the point touching the bottom and the eye floating. This gantry creates a magnetically suspended system with very low friction. As a pulse coil, I salvaged an old 12V relay, broke it apart, and took out the coil from the iron core (about 360ohm resistance). The higher voltages/impedance, the better, so if you have one on hand, use a 24 or 48V relay. The upper frame for the pulse coil needs to be adjusted according to your coil. You can skip printing mine and just print the bottom part. Then glue with double-sided tape your coil at the same height as the magnets. The electrical circuit is very simple: battery-coil-reed switch-on-off switch all in series. I use a little reed switch, 2X14MM normally open. The switch is kept in place by double-sided adhesive tape. Keep it horizontal and align it with the rotor's magnet center at about 15mm from the floor. TIPS: First, when setting up the circuit, find the right battery polarity (the one that pushes apart the magnets on the rotor). Put the coil about 3mm from the rotor magnet and switch on. If the magnet is pushed apart, it's okay; otherwise, reverse the battery polarity. Second, find the right distance of the reed contact. To give the pulse at the right time, note that the reed contact position is not squared in respect to the coil. The reed must anticipate the position of the magnet by about 20 degrees. Find this position by trial and error. This motor doesn't self-start, so after switching it on, you'll need to spin it a bit. To prolong the life of the reed contact, remember to put an inverted diode in parallel with the coil (cathode connected to the + terminal). This will cut voltage spikes created by back-EMF. I used a white LED that flashes nicely while cutting the spikes. The motor needs one coil to start, but using two coils makes spinning force more symmetrical and can reach higher RPMs. My build reached about 500rpm after some adjustments. To keep it spinning, I put two 1.5AA batteries in series (about 2Volts). If you find this nice, feel free to donate. You can also check out my website for more DIY 3D printed parts and circuits: http://www.webalice.it/guaccio1/