These are wonderful little microcomputer projects masquerading as door locks. Inside there’s a processor running a program, with I/O leads going to things like the magnetic strip reader, or the infrared LEDs, and the solenoid, and the lights on the outside.

They are powered entirely by a battery pack, and the circuitry is designed such that it draws almost nil power while idle. The cards are usually magnetic-strip or infrared.

The nice thing about these systems is that the cards are generally expendable; the guest doesn’t have to return them or worry about lost-key charges, the hotel can make them in quantity on the fly, and the combination changes for each new guest in a given room.

You are going to read in relation to the workings of the Electronic Hotel Card Locks and learn if Hotel Card Locks can be used in houses, and their weaknesses and strengths.