There are two switch settings on our Magnetic Field Sensor: Low and High. High means high sensitivity, low means less sensitive. For experiments involving household appliances, you definitely want the High setting. When opening an experiment file in the data collection software, be sure to choose the file that matches the setting of the sensor (high or low). The experiment files for use with this sensor are available at both the High and Low setting, as well as at two different units for magnetic field: Gauss and Telsa (or milliTesla).
If you are unable to get adequate readings using the high setting, it may be that the magnetic field is too weak to measure. As an example, we have found that you can usually pick up the magnetic field near the middle top of an old computer monitor using the following settings:
High switch setting
Sample at about 500 readings per second for 0.2 seconds or so. Rotate the sensor to find the best orientation.
Note: appliance manufacturers work very hard to make sure the magnetic fields outside their appliances are so small that you cannot measure them. You will have better luck with older appliances, when people were not so worried about such things.