“Poetry nights at my local cafe are inspirational,” says Alan Poe. “Trouble is, after hours jotting ideas on my phone between bouts of applause, I don’t even have enough battery left to tweet a haiku. What can I do?”
Knowing when to start and stop clapping at a poetry slam can be awkward. Why not turn the emotional stress into mechanical stress? As someone who also lives life on the edge – by which I mean leaving the house with 2 per cent battery – I think it is time I take matters into my own hands.
Enter piezoelectrics. These materials have a special property that makes them like lemons: when you squeeze them, juice comes out. And you know what they say: when life gives you lemons, make electrical lemonade.
Piezoelectric discs are used everywhere, notably instrument pickups, which turn string vibrations into electrical signals. Wired into a quick test circuit, a firm prod could create enough charge to power an LED, but I foresaw a problem. I was producing alternating current and battery packs mostly require the direct kind.
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No matter. As well as lemons, life has given us diodes. These circuit components only let current pass in one direction, so a clever combination forms a “rectifier” to sort the problem.
I spliced it all onto a cheap battery pack to test. My housemate thought I had seen a spider – she walked in on me aggressively slapping my desk.
How to attach it to me? My first thought was a hanky, a literal trick up my sleeve. But I opted for an elegant pair of gloves. They keep the piezos on my palms and hold the battery pack in a wrist pocket. Perfect for applauding at the opera, maybe less so for rock gigs. I can also charge up with a high five.
They are altruistic too: greater impacts generate a higher voltage, so enthusiastic clapping is encouraged. But even my most heartfelt standing ovation didn’t charge my phone enough to call a cab.
A rough calculation based on figures for an average phone battery showed why: an hour of clapping would only add a few per cent. The world record for the longest applause is 2 hours. You just need some really good poetry.
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