As everyone knows, we travel in public places, will go through the metal security doors, we all know that in order to detect danger, such as knives and other metal objects, when the body carry metal objects through time, security door will alarm, then you know why security doors can be found the metal of the body?
The metal safety inspection door is composed of two door panels and a main engine. The inside of the door panel is made up of a large coil, 6 small coils, and compensation coils and graphite.
The main components of the main host of metal security gate: a main board, the main chip, and the connecting door line, and some of the connecting sluice machines will also be reserved for a line connection.
All metal security doors, are produced by sinusoidal oscillations between 3.5M to 4.9M caused by crystal oscillator, Frequency divider 7.8K sine wave, power amplified by the transistor input door and coil, by large coil electromagnetic emission, received by the door in the 1-18 area of copper coil, then the received signal and the reference signal for comparison, found that after the change, change card output level CPU within 300 ms of 18 location acquisition card scanning, thereby detecting judge metal location.