Cell phone signal shielding devices are mainly used in various test rooms, schools, gas stations, churches, courts, libraries, conference centers (rooms), theaters, hospitals, government, finance, prisons, public security, military heavy places and other places where mobile phones are prohibited. It is understood that the mobile phone signal shielding device on the market can now limit the mobile phone signal of the range of 20 meters from the launching station, such as the range radius of the shield of the P501 of Jin Yuda. The shielding radius is adjustable, and the coverage is up to 30m2. The mobile phone signal shielding device can only shield the mobile phone signal without affecting other electronic devices. Save energy, power is 12W--480W. This article teaches everyone to make a mobile phone signal shield.
Cell phone signal blocker structure
The sawtooth wave is used to control the voltage controlled oscillator to generate a frequency sweep signal of the working frequency band. Each sweep cycle is equal to adding a wide pulse (sinusoidal positive path) and a narrow point at each frequency point in the working frequency band. The pulse (caused by the sawtooth wave) destroys the data exchange between the mobile phone and the base station in the coverage area. The mobile phone cannot get the base station data, and can only display no signal, and of course it cannot communicate.
The sawtooth frequency used in the measured CDMA band is about 30KHz, and the sawtooth frequency used in the other three bands is 10KHz. According to the analysis, the sawtooth wave is not used for measurement here, but the voltage controlled oscillator can be operated. No precision is required. It can be generated by a simple circuit as shown in the figure below.
Circuit diagramThe circuit is simple, the components are easy to obtain, and the accuracy is not high, but it can fully meet the requirements. Here, a sawtooth wave with a lower precision and a longer return stroke might be better? The operating frequency of the voltage-controlled oscillator and RF amplification are relatively high, and there are many points in common. See the figure below.
Cast Iron LV 3PH Asynchronous Motor
Cast Iron Lv 3Ph Asynchronous Motor,Three Phase Asynchronous Cast Iron Motors,Cast Iron Motors,Cast Iron Electric Motor
Yizheng Beide Material Co., Ltd. , https://www.beidevendor.com