I was looking at the Clapp oscillator located here: http://en.wikipedia.org/wiki/Clapp_oscillator Can someone please explain what the transistor is for? Also, since when the oscillator oscillates, the direction of the current flips...does this have any effect on the battery? Lastly, if you disconnect the power from the oscillator the magnetic field across the inductor collapses quickly. Shouldn't a resistor be used somewhere in order for parts not to be damage? Thanks for the replies in advanced.