Submitting this because people have expressed an interest in electronics, and this simple circuit is interesting and this is a nice write up of it.<p>Good luck getting a germanium diode though.<p>The things to make page is cool too, with lots of interesting bits n bobs.<p>For example, on this page he recreates some 17th century demonstration experimental equipment: <a href="http:&#x2F;&#x2F;www.creative-science.org.uk&#x2F;newton_main.html" rel="nofollow">http:&#x2F;&#x2F;www.creative-science.org.uk&#x2F;newton_main.html</a>