Oscillators without transistors

Sounds grossly inefficient. I'm reminded of those Chinese cat things with the waving paw. They seem to have got battery life down to a fine art; must be using a 'joule thief' or some variant thereof I would imagine.

The so-called joule thief is what was called a blocking oscillator back in the days of vacuum tubes and you could find one in every tube type TV. The flyback pulse produces a high voltage because the tube/transistor is cut off abruptly, and the collapsing field produces a voltage spike.

Those moving display gizmos were neat, I used to play with them as a kid. A single D battery or pair of them could keep the thing swinging for a week or two. The magnet was on a half-circle of wire and suspended so it would pass through the coil, working a leaf-switch of a couple of phosphor bronze springs that would repel the magnet as it passed the midpoint. What is impressive was the length of time they's keep working - particularly with the zinc carbon batteries we had in those days.

Transistors cost money back then too. My first blocking oscillator using transistors was pulled from a Radio Electronics magazine for a "sonic shake table" (an interesting gizmo that could make standing waves in particles of flour in an upturned speaker cone - or mercury if you happen to have some) When I got tired of playing with it, I added it to my bicycle for a horn and ran it off the hub mounted alternator.

Was your high school project an electronic vibrator?

Thank you, 73,

No but some years later I made a small air pump using a coil driving a magnet. Other than the heat it developed, it might have made a decent vibrator (of the sex toy variety).