Because of gravity, mercury droplets will flow along the lower part of the container. If two electrodes are contacted at the same time, the switch will close the circuit and turn on the switch.
The shape of the container will also affect the condition of mercury droplets contacting the electrode. For example, the postal bomb uses an inverted V shape, which makes the recipient tilt the postal package without knowing it, close the circuit, and brake the explosion, but the delivery People (or parcel carriers or manufacturers) don’t.
Note: Mercury is toxic to the human body and the environment, so please be careful when using the mercury switch to prevent it from breaking; it should be handled properly when it is no longer used.
(a) Shows a mercury switch encapsulated in a glass case, which is also a more commonly used form. When this mercury switch is tilted at a working angle, the two electrodes can be switched on and off by mercury. Glass tube encapsulation The advantage of the mercury switch is that its working state can be observed from the outside, but the disadvantage is that it is easy to break.
In order to make the glass tube-encapsulated mercury switch not easy to break, people have designed a structure with a plastic protective shell.
(c) is a metal shell mercury switch, the metal shell itself is an electrode.
The mercury switch is to realize the switch on and off according to the movement of the mercury enclosed in the glass or metal casing. Therefore, compared with the mechanical switch, the mercury switch has many characteristics:
①It can be used in harsh environmental conditions. Because the mercury switch is sealed, the mercury inside is isolated from the outside, so it can be used in an environment with oil, steam, dust, and corrosive gases.
②The external force required for on-off is small. Mercury is a metal that can remain liquid at room temperature. Its surface tension and specific gravity are both large. As long as a slight external force causes the mercury switch to tilt, the mercury can move to make the switch on and off.
③ Mercury has good conductivity, and the contact resistance between mercury switch electrodes is generally less than 100mΩ.
④The allowable current of the mercury switch depends on the material of the electrode. The allowable current of tungsten wire electrode is 10A, while the allowable current of general alloy wire is generally 1A.
⑤ Since the on-off of the mercury switch is determined by the gravity of mercury, it can work reliably for a long time.
⑥The contact point of the electrode is liquid contact, without any noise.
⑦Because mercury can flow, as long as the acceleration exceeds the set value, the mercury switch can be turned on or off, so it can be used as a vibration sensitive element.
⑧Small size, various forms, and fully sealed devices.
⑨Simple structure and low price.
The difference between mercury switch and vibration switch
1. All materials of the ball switch can meet the environmental protection requirements, but the mercury switch can’t meet the requirements of its own material.
2. Due to the conduction method of the ball switch, the metal ball is energized with the trigger pin to generate a signal. Because the contact area between the ball and the trigger pin is small and the ball is movable, the conduction sometimes flashes off, and the mercury The switch is mercury in contact with the trigger terminal. Because mercury is liquid, the contact surface is large and stable. Generally speaking, the conduction effect is more stable.
3. The ball switch is a metal shell with good structural strength.
Mercury is toxic to the human body and the environment, so please be careful when using the mercury switch to prevent it from breaking; it should be handled properly when it is no longer used.