<story><title>A clever “perpetual motion” device [video]</title><url>https://www.youtube.com/watch?v=r_LG8FDt51U</url></story><parent_chain><item><author>londons_explore</author><text>This circuit is awfully complex....    it&amp;#x27;s possible to do the same with a far simpler circuit if you use the same coil for sensing and accelerating the ball.&lt;p&gt;A small microcontroller could do both - perhaps even with low enough power that the whole circuit could stay turned on for years on a charge (when not flinging the ball).&lt;p&gt;Looking at the total energy you need to impart on the ball, you should be able to do that with a far smaller coil and many fewer capacitors as long as you have a suitably shaped steel core to keep the flux path low.   I suspect you might be able to do it with no capacitors at all, since modern lithium cells are perfectly happy to deliver 100 amps for a few milliseconds.</text></item></parent_chain><comment><author>lolinder</author><text>&amp;gt; This circuit is awfully complex ... A small microcontroller could do both&lt;p&gt;Adding a microcontroller might reduce the number of components used, but it&amp;#x27;s a bit disingenuous to claim the result is &amp;quot;simpler&amp;quot;.</text></comment>
<story><title>A clever “perpetual motion” device [video]</title><url>https://www.youtube.com/watch?v=r_LG8FDt51U</url></story><parent_chain><item><author>londons_explore</author><text>This circuit is awfully complex....    it&amp;#x27;s possible to do the same with a far simpler circuit if you use the same coil for sensing and accelerating the ball.&lt;p&gt;A small microcontroller could do both - perhaps even with low enough power that the whole circuit could stay turned on for years on a charge (when not flinging the ball).&lt;p&gt;Looking at the total energy you need to impart on the ball, you should be able to do that with a far smaller coil and many fewer capacitors as long as you have a suitably shaped steel core to keep the flux path low.   I suspect you might be able to do it with no capacitors at all, since modern lithium cells are perfectly happy to deliver 100 amps for a few milliseconds.</text></item></parent_chain><comment><author>mcpackieh</author><text>I think you could drop coil sensing of the ball entirely and simply switch the electromagnet using the metal ball contacting the two metal rails.   A dialectic gap in the rails near the bottom of the track could turn the electromagnet off at the right moment.</text></comment>