1. the appearance is divided into outer frame, inner frame and functional parts. the inner and outer frames of a good key switch are made of pc material. the scientific name of pc material is polycarbonate, commonly known as bulletproof glue. it is not easy to stain and has a smooth appearance. generally speaking, you can see that the outstanding parts behind the switch are functional parts. if it is white, 80% are pc. if it is black, you should pay attention to asking the shopping guide. pc materials are all white, of course, do not remove the yeast that has added color.
2. then the function piece inside has to be opened before the lever can be seen. after opening the function piece, there is something like a seesaw inside. we call it a seesaw. usually a good switch is a seesaw without sliding. they are all sliding rockers. there is a silver-white contact at one end of the rocker. touching the key switch is to rely on him to turn on and off the current. good switch contacts are all silver alloys, some are silver-nickel alloys, and some are silver-chromium alloy, no matter what alloy it is, the purpose is to enhance the hardness of silver and increase its melting point to avoid melting silver when the current is too large; and the rocker is a current-carrying member, which is used to carry current, and its raw material is tin phosphor bronze, you can also ask the clerk, if he says it's brass, don't buy it. some of this is because of the layout inside, you can't see it when you buy it, so i'll tell you, after you ask the manufacturer, you can't buy it. can know.
3. if the hole of the socket is seen from the outside, if something colored or white covers the copper sheet that cannot be seen inside, then it proves that there is a maintenance door layout, and you can take a hairpin or a hard object to poke it against the single hole, and you can't go in to prove that there is a self-locking device, which is a good socket. if there is no maintenance door, you must not buy it. the so-called maintenance doors of the brａnd are all plastic, and the products are all reinforced nylon, which is fireproof and durable. the maintenance door can avoid the barrel switch when the child is cunning. this is very important.
4. look at its wiring method. the current wiring method adopts the fast wiring method, and the card wiring method is used, that is, the wire is stripped out without screws, and inserted directly behind the switch
it can be done in the wiring hole. we may think that this is nothing, and there is no contact with the user. it is only convenient for the electrician, but the wiring method can detect the power consumption of the switch, so don’t neglect it;
we can also use the general double-hole platen layout. this can be seen from the appearance. you turn the switch over and see that there are some prominent parts on the back, that is, the functional parts. there are several holes behind it, you can look through the holes , if you see a screw and a small board - there are two holes on the side, and there are marks of a few millimeters to a few millimeters around the holes, it proves that this is the layout
.