You will find that why touch the switch and even four feet, is because of what this reason, and what role? Today I will explain these aspects to you for your convenience.

There are two functions of tap switch: one is normally open type and the other is normally closed type. The most common type is the normally open type. The normally open type refers to the line is generally disconnected. Press the key handle gently to touch the contact between the shrapnel and the shot point of the base. At this time, the switch is regarded as the conduction, and the release key handle shrapnel is separated from the shot point. At this time, the switch is regarded as the separation, and the product performance is OK. When the line is disconnected, the resistance of the two circuits is 30m Ω. When the switch is turned on, the contact resistance of the two circuits is 0. At this time, the switch performance is very good. Normally closed type is relatively rare, because it is not in line with the conventional product design. Normally, the switch is on, and when the switch is touched, the circuit and function are disconnected. The resistance value of the switch is the opposite of that of the normally open switch, so it is generally not recommended. The figure below shows the normally open tap switch:

Whether it is a normally open or normally closed light touch switch, it must be composed of more than two pins, so as to form a group of switch functions, which are normally two, four and five pins. Why is there a five foot switch? Because the fifth foot is used for grounding. I think you all know what the grounding foot is used for. Of course, there are also three feet. Generally, there are more side pressure on the three feet. The third foot is designed for fixing, so you can use it at ease. It's OK to press hard. In the figure below, we can see the two pin circuit at a glance. Let me explain how to connect the four pins of the switch by tapping them! Under normal circumstances, 1 and 2 are a group of conduction, 3 and 4 are a group of conduction. When the switch is touched, 1 and 3 are a group, 2 and 4 are a group. It is right to design the function of the switch in this way.