:yodel: :yoda: :emperor: :cleaning:
2,088,600 million RPM, 34,810 rev per sec, 733mph, and 7.3 million G's
I been watching YT videos on the pmbo comps and decided to finally try a high rpm motor. I hesitated for a long while because of the exotic coils being made. I said lets get a hall sensor out of a dc brushless fan (40mm), connector up to a larger drive fet, wrap a simple coils and give it a spin. A few days playing with it I was just above 1Mrpm. Never got a video of it, then it sat on the shelf for 2 years, then I saw another video and dug out the project again. Decided to update my drive circuit by adding a pre driver to drive the gate and as an option build an identical second driver for push/pull. I tried the push/pull but it really did not improve on what I was doing, probably never was doing it correctly, not sure, might revisit it again.
I broke my personal record with 1,140,901rpm, 19.02KHz, maximum ball equator speed = 668mph (979kph) and 3.64 million G's at the equator, at that point, the ball has a slight issue at that point in time. :bliss: Before getting to a million rpm, around 8~900,000, if ran long enough, the ball would wear down it silver coating and sometime shed its chrome skin. :cleaning:
I made my first video and put a little incorrect data (lower mph numbers) do to me thinking I was using a 3mm ball, when it was 5mm. Here is my corrected video:
It is burning about 30W (5V, 6A).
My thoughts on coils with my little experience. Reading "The density of flux lines is inversely proportional to the square of the distance from the source", I figured no need to make a large coil (although those starship coils do look very interesting), a simple 10~15 turn one inch diam coil made in 20 seconds exceeded the 5mm balls rpm capability. 0rpm to explosion is about 2.2 seconds in these 5mm neo balls.
I have a few ideas on higher rpm, parts are ordered. More info here: https://www.rcgroups.com/forums/member.php?u=91160
FYI, I have two layers of protection to my face and three layers to my eyes, kids, dont try this at home, leave it to the professionals. :deathstar: