Sadly the premise that it operates on a thermal principle has been pretty much debunked - it operates on electromagnetism, due to the induced EMF when the ball bearing rotates through a magnetic field caused by the current through it. Here’s a paper describing the effect (which has been experimentally verified)... http://www.physics.princeton.edu/~mcdonald/examples/motor.pd...
I built one of these at university as a research project and it works well (albeit drawing a huge amount of current!). Interestingly enough it works just as well in either direction, depending which way you give it an initial push - the polarity of the DC terminals doesn’t matter at all!
The parent is replying to the article itself, which describes in glorious detail the apparent principle of operation. The youtube video linked downthread also has a description with the same thermal expansion explanation.
Sadly the premise that it operates on a thermal principle has been pretty much debunked - it operates instead on electromagnetism, due to the induced EMF when the ball bearing rotates through a magnetic field caused by the current through it. Here’s a paper describing the effect (which has been experimentally verified)... https://news.ycombinator.com/item?id=20415755
I built one of these at university as a research project and it works well (albeit drawing a huge amount of current!). Interestingly enough it works just as well in either direction, depending which way you give it an initial push - the polarity of the DC terminals doesn’t matter at all!
I sort-of feel that anything which uses electricity purely for a thermal effect, is actually in the carnot engine space and not actually "electric" in any meaningful sense of the word. They could have modified a stanley steamer to boil water electrically, and made similar claims (ball bearings aside)
I wonder if you could put a current regulator on it that would provide the minimum current needed to achieve a certain RPM. Seems like the heat issue could just be that after it reaches its maximum speed, the excess current is just wastedin ohmic heating.
I built one of these at university as a research project and it works well (albeit drawing a huge amount of current!). Interestingly enough it works just as well in either direction, depending which way you give it an initial push - the polarity of the DC terminals doesn’t matter at all!