Homemade Damped Oscillations

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I learned an easy way to make ringdowns (damped oscillations). By inductively coupling the output of a square wave generator to a tuned circuit, the very high Q oscillations may be viewed. This was all done cheaply and quickly. This is a very demonstrative circuit for understanding oscillations.

Damped oscillations are the natural response of a tuned circuit. The differential equation describing it is fairly easy to solve.

Here's my setup:

To get square waves, I wired a 555 timer to be in astable mode. I used a similar circuit to build my digital clock. The square waves have this appearance:

Here's some nice pictures of ringdowns:

Adding more inductor, a lower frequency is viewed. Note that the decay is more rapid too, since the inductor has an internal resistance.

That's it!

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