User Manual

46
Lesson 16 Mercury Switch
Introduction
Similar to a tilt switch, a mercury switch is used to detect slight inclinations of a large angle.
A mercury switch (also known as a mercury tilt switch) is a switch which opens and closes
an electrical circuit through a small amount of liquid mercury.
Mercury switches have one or more sets of electrical contacts in a sealed glass envelope
which contains a bead of mercury. The envelope may also contain air, an inert gas, or a
vacuum. Gravity is constantly pulling the drop of mercury to the lowest point in the envelope.
When the switch is tilted in the appropriate direction, the mercury touches a set of contacts,
thus completing the electrical circuit through those contacts. Tilting the switch the opposite
direction causes the mercury to move away from that set of contacts, thus breaking that
circuit.
Components
- 1 * SunFounder Uno board
- 1 * USB data cable
- 1 * Mercury switch module
- Several jumper wires
Experimental Principle
Since the LED has been attached to pin 13, just connect pin S to D2 of the SunFounder Uno
board. When the mercury switch inducts tilt signals, the LED will be on. Otherwise it will be off.
Note: Mercury is harmful to human body and environment. Thus, please BE CAREFUL when
using a mercury switch in case of glass breaking. It should also be properly handled if it's no
longer used.
SunFounder