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Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061
seems that a "small jolt" at the right frequency can increase efficiency of a piezoelectric energy harvesting system.
This is in fact a variation on the old amateur radio trick of "regenerative feedback"- early receivers increased their gain by feeding back some of the output to the input to increase sensitivity and selectivity.
A related phenomenon is the increase in available signal when pseudorandom noise is injected during preprocessing and then removed from the system post processing- it appears that a weak signal can be boosted in this way in the human ear due to the nonlinear nature of the sensors.
As an intriguing experiment, my thought is to expose the phosphor of one of those tritium lights to extremely short pulses from a UV LED, causing the output power to rise above the level needed for an InGaN green LED to extract useful energy.
Still consistent with thermodynamics as the small trickle of energy into the phosphor is too weak to generate significant power but driving it with a pulsed UV LED "tickles" it into a higher energy state where energy can be extracted before the excited state decays.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Conundrum wrote ...
This is in fact a variation on the old amateur radio trick of "regenerative feedback"- early receivers increased their gain by feeding back some of the output to the input to increase sensitivity and selectivity.
Radio amateurs may have enjoyed the relative simplicity of super-regenerative receivers, (SRR) but they were widely used in military equipment in the 1940s, such as the tank-to-tank VHF B set of the famous Wireless Set No. 19, the 200MHz "Eureka" Radar Interrogator-Beacon System, the American TBY & TBY-1 UHF transmitter-receiver, and many similar offerings from the Axis powers.
Just when SRRs seemed about to fossilize forever, they have enjoyed a recent resurgence of interest, with all sorts of applications devised for them.
Rumley S, Superregenerative Receivers for Remote Keyless Access Applications A high performance low-cost design approach for wireless activation
Rohde UL and Poddar AK Super-regenerative Receiver A planar injection mode-coupled SRR... a cost effective alternative to expensive high Q BAW/SAW resonator SROs for SRR applications.
As for an analogy between SRR operation and this newly reported piezoelectric phenomenon, I would have to know a lot more about it to form a view.
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Tesla technology improves energy extraction from piezoelectric vibrations
