Extreme Low-Tech Communication
...oice vibrating the microphone (which was a re-purposed speaker). If you want to build your own here’s the circuit schematic and more details. And here’s Rainey, back in 2009, using El Silbo: https://www.youtube.com/watch?v=f6G_yGDbgEY#t=0 On a side note, can we please apply Ham radio’s level of detail and open source spirit to the world of backyard vegetable gardening?...