In a hotel room, I need to plug in a card to get electricity. Why is there electricity after the card is inserted?

The hotel uses a plug-in card power switch, so the card is plugged in before power is available.

The working principle of the card power switch is as follows:

The card power switch consists of three parts: high and low voltage power conversion part, identification card part and output part.

the high-low voltage conversion part rectifies the alternating current into a DC low-voltage power supply for the identification part and the output part, and the identification card part detects whether the inserted card meets the preset standard.

Extended information:

The development process of power take-off switch is synchronized with hotel lock, because the power take-off switch must be matched with the door card type of hotel lock because it needs to use the door card to get power.

1. Mechanical power take-off switch

The early power take-off switch was actually a mechanical rocker switch, which connected the two contacts of the power supply by inserting a key card. Thus, when the guest leaves the room, the contact is disconnected and the power supply of the room is cut off while taking out the key card.

2, photoelectric power switch

With the advent of the magnetic card hotel lock, only one magnetic card is needed to open the door and get electricity, and the photoelectric power switch appears. Its principle is that a pair of infrared rays are turned on or off through the card, the control circuit detects the turn-on and turn-off of infrared rays, and the power supply is output through the relay. The power switch of this principle is also called universal power switch. There are still a few hotels using it.

3. The IC card power switch

is mainly used to get power through the contact IC card, mainly to detect the chip pin of the IC card and judge whether there is a card inserted and whether the IC card is inserted to output power. At present, the market share is also relatively small.

Baidu Encyclopedia-Plug-in card power switch