Do not connect a speaker directly to a headphone jack (Speaker Impedance)

During the early days of exploring the headphone jack, we did some crazy stuff all in the name of science. And although many of them resulted in ecstatic moments of awe that we cherished, sometimes things went a little out of hand. But we learned important things from this experience.

In one of our previous posts, we showed you how we nearly fried our headphone jack ( appropriately titled Don’t do this! ). And in this post we will show you how to keep your USB port safe while playing around with speakers.

Speaker Impedance


It is important to note that the speaker offers resistance to the flow of electrons. And when dealing with DC, we call it resistance but when one is dealing with AC it goes by the name of impedance.

And by virtue of Ohm’s law , we get that:

Lower the impedance → more current → greater load → increased power

Raise the impedance → less current → smaller load → decreased power

And as a general rule of thumb, small speakers (like the ones on your headphone) offer really high resistance to the flow of current and larger ones offer little to no resistance at all.

This caused us an Arduino because we accidentally connected ~4 Ohm speaker to the Arduino. And due to its low impedance, it became power greedy and destroyed it while also temporarily shutting down the USB port. So, yet another thing that one must be careful about.

How to be careful ?

Now that you know about speaker impedance and what it can do, we strongly suggest that you read the following article  to enlighten yourself:

Understanding Speaker Impedance






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