user1496: If you connect your arduino to a motor you use this schematic:

However, when it comes to buzzers, which also have a coil, no one protects the circuit:

What the hell is going on? Are these just buzzers "coiless"? How can I find the type of buzzer I have?

user4143: That kind of "buzzer" doesn't have a coil.  It is a "Piezo Transducer" and uses a crystal to produce the sound.
When you're using a real speaker and producing sound you are doing it very differently to switching a motor or a relay on and off.  You're generating a much smoother waveform and you don't have the sharp "ON-OFF" that causes a collapse of the magnetic field.  You're actually gradually reducing the power and then reversing it to remove the magnetic field then apply a new one in the opposite direction (if you have wired it right of course).
Also the currents involved in driving a speaker like that are minuscule compared to switching a relay, especially when driven direct from the Arduino.  For louder volumes you will use an amplifier, and that deals with the whole protection within itself since it is designed to drive a speaker.

1496: <p>If you connect your arduino to a motor you use this schematic:</p>

<p><img src="https://i.stack.imgur.com/ibbFi.png" alt="enter image description here"></p>

<p>However, when it comes to buzzers, which also have a coil, no one protects the circuit:</p>

<p><img src="https://i.stack.imgur.com/JMqnY.png" alt="enter image description here"></p>

<p>What the hell is going on? Are these just buzzers "coiless"? How can I find the type of buzzer I have?</p>
 4143: <p>That kind of "buzzer" doesn't have a coil.  It is a "Piezo Transducer" and uses a crystal to produce the sound.</p>

<p>When you're using a real speaker and producing sound you are doing it very differently to switching a motor or a relay on and off.  You're generating a much smoother waveform and you don't have the sharp "ON-OFF" that causes a collapse of the magnetic field.  You're actually gradually reducing the power and then reversing it to remove the magnetic field then apply a new one in the opposite direction (if you have wired it right of course).</p>

<p>Also the currents involved in driving a speaker like that are minuscule compared to switching a relay, especially when driven direct from the Arduino.  For louder volumes you will use an amplifier, and that deals with the whole protection within itself since it is designed to drive a speaker.</p>
