Delay line oscillator
A delay line oscillator is a form of electronic oscillator that uses a delay line as its principal timing element.
The circuit is set to oscillate by inverting the output of the delay line and feeding that signal back to the input of the delay line with appropriate amplification. The simplest style of delay line oscillator, when properly designed, will oscillate with period exactly two times the delay period of the delay line. Additional outputs that are correlated in frequency with the main output but vary in phase can be derived by using additional taps from within the delay line