[fernly]

"My neighbor had just got a dog that was always barking. So I got tweeter, built up a simple 30kHz oscillator using a LM324. Set the two LM383 to swing rail to rail. Got a lantern battery that could put out the power. Then connected the tweeter."

Paging Steve Gibson: somebody reinvented your dog silencer[1][2]!

[1] https://www.grc.com/tqc/TheQuietCanine.htm

[2] https://groups.google.com/forum/#!topic/portable-sound-blast...

[justtopost]

I think nearly every budding ee has built a variation of this at some point.