Making Sounds - Exploring Arduino: Tools and Techniques for Engineering Wizardry - page 98

of the end pins connects to the 150Ω resistor. When the knob is turned all the
way toward the unconnected terminal, the entire resistance of the potentiometer
is added to the series resistance of the 150Ω resistor, and the volume lowers.
When the knob is turned all the way toward the connected end terminal, it
adds no resistance to the series, and the speaker is at max volume. Referencing
the schematic in Figure 5-4, wire your speaker to the Arduino. Then, confirm
your wiring using the diagram in Figure 5-5.
Figure 5-5: Speaker wiring diagram