Joule thief 1.5 v dc to resonating sin

It is out of resonance, see the beats?

A joule thief or a blocking oscillator is nothing more than an overdriven maisner oscillator. The only difference is that in a maisner oscillator the input replenishes the output losses, very gently, it's a soft start oscillator, while in a joule thief the output is switched very vigorously, thus slamming it right into the two extremes, and as we know, coils typically don't like their power supply cut off sharply so they create a voltage spike of their own, to dump the excess current, untill the magnetic field collapses. Bottom line is, a sloppy designed Maisner oscillator can be a good joule thief, and a cleverly designed joule thief can make a good sinewave oscillator.