<br><div><a href="http://en.wikipedia.org/wiki/Spark-gap_transmitter">http://en.wikipedia.org/wiki/Spark-gap_transmitter</a></div><div><br></div><div><a href="https://www.youtube.com/watch?v=XDWkvx1DWHg">https://www.youtube.com/watch?v=XDWkvx1DWHg</a></div>
<div><br></div><div><a href="http://www.alexander.n.se/">http://www.alexander.n.se/</a><br><br><a href="http://www.bobsoldphones.net/Pages/Essays/Hughes/Hughes.htm">http://www.bobsoldphones.net/Pages/Essays/Hughes/Hughes.htm</a><br>
<br><a href="http://noisejunk.eu/index.php?page=instruments&instrument_id=27">http://noisejunk.eu/index.php?page=instruments&instrument_id=27</a></div>