That is an average 130,000 rpm acceleration every 1ms for 25ms!
After many many attempts for personal rpm record, I did get my record of 3.34 Mrpm on Friday (5-17-2019). I always set the scope vertical cursors to my current record (in microseconds), so I can see when I beat my personal best. I usually prepare about 10~15 balls for testing that day, one day, I got to this one special ball, I guess all things were just right (ball/container/angle/settings). What happened was amazing and unbelievable, with about 250 watts (18V ~13A) input into the system. The first hall sensor trigger, it gave a ~0.25 second burst, I could hear the power supply give a quick 60Hz hum, sucking some big current, then the scope displayed high 2 million rpms! The major keys it was legit was no vibrations and the ball was still spinning down from momentum. I have been running the scope at 10us/div (since going for 2+ mil), but I decided to get the big picture, zoomed out the scope to 100ms/div (1sec across the scope) then set single trigger and tried again, moved the hall sensor into position and it happened again, a burst of around 250ms then hall stops triggering the coil. I zoom the scope into the end of the coil drive signal, this time just over 3 million in a quarter second! I stopped to think about it, no Ford transmission vib's, just pure signing spinning ball. Blown away I called a friend to witness what happened, I did it 4 more times, the most impressive time was in the picture, it shows 0 rpm to 3.2 million rpm in ~25ms!. That is an average 130Krpm acceleration every 1ms for 25ms. This is what happens when you pump in ~250W (1/3HP) to spin a 3mm ball that weighs nothing (~0.11g) AND everything is close to optimal. I like the technical challenge, thinking of new ideas, building, testing, tuning, retesting, repeat.
Projects that are not for RC, but are cool and worthy of development.
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