Open-Source Microcontrollers for Science - Open-Source Lab: How to Build Your Own Hardware and Reduce Research Costs - page 70

FIGURE 4.11 Wiring diagram for the humidifier.
Next, connect the fan wires properly respecting the polarity as shown in Figure 4.12 . Con-
nect the relay to Arduino Digital Pin 41 .
FIGURE 4.12 Wiring diagram for the fan.
For cooling in the prototype Bear Chamber we used a dorm refrigerator, but depending on
your application you may want a smaller or larger chamber. The chamber will be made up by
the size of your refrigerator or cooler. Refrigerator/coolers usually have a thermostat that is
connected to their main protection relay. To find it, you will need the cooler's wiring diagram
or manual. If you buy it new, obtaining the wiring diagram is not a problem. Similarly, you