Pulse Motors: PerPenduPetulum: Auto Triggered Pulse Pendulum

Here’s the latest gadget, derived from a project I saw on “Nuts & Volts”. Schematic is given at the end of the video.

This is a mechanically resonant system. The pendulum’s rate of swing depends only on the length of the suspension, as we recall from basic physics. The period is thus constant, no matter the amplitude of swing. So, just like pushing a child on a swing, if the pendulum is “pushed” a tiny bit at the right time, the swing — the resonance amplitude — is pumped up to some great value, much higher than could be achieved by a single push alone.

Energy is stored in the resonant swinging. Losses also build up: air resistance, etc. depend on the speed of the pendulum which of course increases as the amplitude increases, since the period is constant. So eventually a point is reached where losses equal the per-pulse input of energy and the amplitude then is constant.

If one extracts energy from the pendulum at a greater rate than is being supplied by the coil and driver system, then the amplitude will decrease.

The original project in Nuts&Volts was intended for use with a solar cell for power. I’ll try that next.

Thanks for watching!

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