Power from Vibration

Free RF energy would probably be easier as there is a lot of it spread over a large bandwidth.

fred

The two obvious generation technologies are piezoelectric and electromagnetic. You can find some interesting references (including MEMS technology) online. Probably not applicable to your micropower application, but a really effective vibration energy source could actually damp the vibration as an automotive "shock absorber" does.

I would like to experiment with some ultra low power electronics powered from ambient vibration. Do any of you have any experience with this type of technology? What power-generation devices would you recommend?

-Robert Scott Ypsilanti, Michigan

The value of an answer to your question depends a lot on the interpretation of the word 'ultra'. If your electronics is in an environment with some machinery around, you can consider a supermagnet mounted on a reed, mechanically tuned to produce maximum amplitude. The magnet's field would be coupled to a coil of wire. A variation would be a rotary pendulum, ala self-winding watches of yesteryear. This also may be of interest:

Paul Mathews

Ski makers have borrowed a damped piezo laminate structure from aircraft makers.

This is a really effective vibration energy source that actually does damp the vibration as an automotive "shock absorber" does, as Spehro suggested.

Doug

Thanks for the link. Actually, the applications I am thinking of are as you described, on the airframe of a small plane with a running engine shaking everything.

-Robert Scott Ypsilanti, Michigan

Have a look at available info on super magnets and choose one of suitable mass, so as not to burden the plane much. Learn about magnetic paths, simple harmonic motion, and Ampere's Law. It all boils down to maximizing the rate of change of flux density in a coil of wire, with more turns producing more voltage. It should be fairly easy to produce power to run some low power electronics from some strong vibrations, particularly if vibration frequency is relatively constant. Paul Mathews

Check out Radio Australia's "Innovations" program for a few weeks back. They did a segment on an Australian developer/manufacturer of ambient vibration generators, although I think they had a different name for them. for a start.

Mark Zenier snipped-for-privacy@eskimo.com Washington State resident

If you have a running engine, why not just get power from it?

??? Rich

A mechanically 'stiff' transducer, such as a piezo unit, will work best near a vibration antinode but a 'softer' electromagnetic transducer will benefit from the increased vibration amplitude at an antinode (e.g. the middle of a panel).

..because the application is inside the fuel tank. Wires are difficult to run.

-Robert Scott Ypsilanti, Michigan

"Analytical Models to Predict Power Harvesting with Piezoelectric Materials" T.Eggborn

RL

The precis looks really kewl; I'll have to read the paper.

Mark L. Fergerson

I would add some mass to a loudspeaker coil and connect the coil to a step up transformer (try a 3V to mains winding on a power plug transformer) Full wave recitify the resultant from the mains winding and charge a capacitor. Now apply to a switching regulator to optimise to the voltage you require.

Match the impedance of the gen to the source impedance. I dont mean electrically, but mechanically. This makes a big difference. Stiff piezo is higher impedance than soft moving coil.

Mounting a weight to the centre of a piezo disc and attaching edges to structure is a very simple way to get energy from vibration. Whatever you use, in a fuel tank you must ensure that whatever goes on there is no possibility of s spark. Piezos are inherently spark-capable and spark prone.

NT