Below is a step-by-step guide on how I build a signal jammer on my own. Since most mobile phones run on this frequency, this jammer can block the cell phone signal at 800 MHz. The oscillating wave generator played the role of the voltage control generator. Of course, if you have no experience with radio devices, it will be problematic to assemble such a device, but it works great!

Next, I took a clock generator tuned to 45 MHz, to which the local oscillator port on the receiver chip responds, resulting in noise. It is also necessary to equalize the resistance in the clock generator and the local oscillator port. To do this, I sent a signal from the local generator of electrical oscillations of the receiver through the resistance matching network.

The oscillator port (the RF input) must have an 800 MHz antenna, and the RF output must be connected to a signal amplifier, which increases the device’s output power by 15-16 dBm. Then the already amplified signal hits the outgoing antenna.

The frequency difference between any mobile phone’s incoming and outgoing signals tuned to 800 MHz is exactly 45 MHz.

Thus, if someone is nearby and talking on the phone, my jammer will simply send the signal to block the phone, and the person will no longer hear anything but his own voice.

It is worth noting that this blocker can jam tracking devices that track cars using their navigation devices. For example, a GPS jammer and exchange data on the same frequency of 800 MHz.

The device can be useful even to sappers – to drown out the detonator signal sent through the cellular network.

A battered aluminum box became the body, and the VHF connectors from the old Motorola turned into input/output devices. As a power source for the new cell phone jammer, I installed a 9V battery and a voltage regulator. Inside, I made a foam partition, protecting the battery from other device parts. The same Motorola gave the antennas attached to the VHF connectors to the new muffler. I also placed a switch on the case.

To make a cell phone jammer, you will need to combine some parts into one. Here is their list:

  • Voltage Controlled Generator (VCO)
  • Tuning Circuit (for selecting the desired frequency to jam)
  • Source of Interference (usually built into the Tuning Circuit)
  • RF Amplification Unit (the so-called “amplifier stage”)
  • Transmitting Antenna

The VCO is the most important part. It is like the heart of your jammer. The VCO produces an RF signal that will communicate with the device being blocked. First of all, you must select the frequencies to be used by your jammer. Here is a list of the main communication standards:

  • AMPS (800MHz)
  • PCS (800MHz, 1800MHz, and 1900MHz)
  • GSM (850MHz and 1900MHz in America, 900MHz and 1800MHz in Europe)
  • GPS (main civil frequencies 1227MHz and 1575MHz)
  • Wi-Fi/Bluetooth (2400MHz – 2500MHz)
  • RFID (also known as UHF/VHF, 14MHz – 400MHz, 800MHz, and 2450MHz)

You also need to think about the size of the future jammer as you can create

The tuning circuit can be of two types: open circuit and feedback. The open circuit is simple and requires only a few additional passive components. The sawtooth generator causes the VCO to go from low to high frequency. The closed loop circuit uses a PLL to adjust and hold the frequency of the VCO at the same level. For this purpose, you need to use a microcontroller. It is programmed once and connected to the VCO, so it is not configurable. The RF Amplifier is what you need if you want to expand the coverage of your jammer along with the signal strength. The more power your signal jammer has, the wider the radius of its suppression. The price of this is, as you probably guessed, the device’s operating time. More power equals less battery life.

A fairly wide selection of amplifying stages on the market for electronic components (7dBm, 17dBm, and even 20+dBm). However, it should be borne in mind that the greater the power, the shorter the device’s operating time.

The Transmitting Antenna is the device that transmits the signals generated by your jammer. The main characteristic of the antenna is VSWR (Voltage Standing Wave Ratio). If your antenna’s VSWR is three or lower, then that’s it because the return loss of this antenna is minimal.

We use SMA antennas as they are very easy to remove or replace. It should also be mentioned that omnidirectional antennas are preferred if you don’t want to constantly point your jammer at the target of jamming like a TV remote control.

The Power Source keeps your creation alive. Typically, mobile phone jammers use 5V DC to operate. Therefore, you can use a lithium-ion battery as a power source. You will need an AC adapter if you use a conventional power supply. The network adapter can be a controlled capacitor voltage doubler or an inductor switching boost regulator.

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