Fred points out this schematic for a rather interesting radiotelephone transmitter instantaneously powered by the operator's voice -
One of the neatest minimalist amateur radio transmitter circuits around - this one is voice powered - it provides DSB, (double side band)modulation and power from an ordinary 8-ohm speaker - if are in doubt that the circuit works, the maker has the contacts and the voice recordings to prove it!
An explanation of how it works + schematic and audio sample can be found on the El Silbo page.
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More contributors: Mark Frauenfelder (Editor-in-Chief, MAKE magazine), Kipp Bradford (Technical Consultant/Writer), Chris Connors (Education), Diana Eng (Guest Author), Peter Horvath (Intern), Brian Jepson (O'Reilly Media), Robert Bruce Thompson (Science Room)
Behind the Scenes at MAKE and CRAFT
In January, many of the remote MAKE/CRAFT team members (myself included) convened at the Maker Media headquarters at O'Reilly Media in Sebastopol, California. Take a look behind the scenes of your favorite DIY publications as Goli Mohammadi gives us...
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