As one of those pendulum enthusiasts, I guess it's time for my 2-bits worth. For the younger generations 2-bits is $.25 worth.He is after what pendulum enthusiasts are also searching for - the Holly Grail of self amplifying oscillation. The question is ... do you think he has the answer ?
I have never looked at a pendulum as a self-amplifying oscillator. All a pendulum can do is in a sense store energy that will be released on falling. We all agree that there is loss due to friction and gravity therefore input must be maintained. A pendulum does not offer a free ride.
Everything is said to have a resonant frequency, if that frequency is induced it will set up a vibration that is easily maintained and will amplify only as long as what ever source is supplying said frequency is kept constant. If maintained the object will self-destruct as Georg implies.
The first example that come to my mind is a female singer capable of shattering crystal glass. Another is the rubber motor mounts in your automobile. Without them, if the engine RPM ever produced the resonance of the auto body your car would self-destruct. Now some of you will probably say poo poo to this, so I recommend you talk to an auto designer or engineer. My third example would be large windmill blades that experience metal fatigue due wind finding blade resonance.
I agree with bill, that a resonance will build but you cannot use it as an outside energy force. Any attempt to connect or draw from it will change the resonance of the object in question.
Ralph