Typically a Schmitt Trigger can very easily be made to oscillate. You just need to make a frequency determining RC or LC network, that will oscillate between the two threshold levels of the Schmitt Trigger and make a feedback for it to sense this oscillation. Now when the oscillations pass over the thresholds they will make the trigger response to this passing. If you can add a way to make the trigger pull some of the LC's energy at just that moment, you've got yourself an oscillator. Only problem is, this thing tends to work in a very specific voltage range. Anyway enjoy :)
