Cell phone signal jammer is installed in quiet areas, such as schools or universities, but… how exactly does this instrument block cell phones? These locking instruments prevent mobile devices from receiving signals from base stations. While it may sound like a complicated process, making your own phone blocker isn’t that difficult. However, you should know that in many countries (including the United States) they are illegal and subject to large federal fines, in addition to criminal prosecution. Who knows what could interfere …
1. Understand the principles of operation. This cellular signal blocker operates with the GSM800 frequency, since most mobile phones use it to operate. The VCO selected is a sweeping oscillator, which is very effective but can be difficult to build for beginners who do not have good RF testing equipment.
As a noise source you can use a 45MHZ clock oscillator, which is the local oscillator port located on the mini-circuit mixer. There is also an impedance matching network for the local oscillator signal to pass through. It is used to match the impedances of the oscillators and the mixer port.
The RF input (which is the mixer port) connects to the first 800MHz cell antenna, and the RF output is sent to the mini-circuit amplifier. This amplifier increases the output power by 15-16 dbm. Then the amplified signal is sent to the second antenna of the cell phone.
2. Consider how it works. All cell phones using GSM800 always separate the transmitted and received frequencies at 45MHz. So when the mobile phone tries to call, it is blocked by its own signal coming back to you! Isn’t it cool? So when the chatter of the phone irritates you, turn on the blocker so that the criminal hears his own voice on his cell phone. By the way, you can also use this cell phone signal blocker to block any cell-based tracking system that uses your GPS to track and record the movements of your car. And you can probably block improvised explosive devices that are detonated using cell phones. The mixer that is used is designed to work up to 600 MHz, but in this case it works very well. The RF amplifier does its job quite well even though it consumes additional power.
3 Use an old aluminum box as a frame for the jammer and some old UHF connectors from a Motorola cell phone for input and output.
4 Connect the RF connectors to the circuit.
5 Use a nine-volt battery and a voltage regulator to power all components. Place the battery inside and separate it from the rest of the components using foam rubber.
Flip the on / off switch at the top.
6 Screw the input and output antennas (also from an old Motorola cell phone) to the UHF connectors.
7 Your cell phone blocker is ready. Enjoy it!