For a long-long time many people were looking for this cool recipe of making something interesting for yourself. And I was one of them until last days. In my quest I came across the Jammer Store blog post called How To Make Your Cell Phone Jammer: DIY Guide. It inspired me to make something like that by myself.

All necessary info, schemes and pictures are there, so I tried. The result is represented in this humble guide for you.

Step 1: The Basics

This signal jammer uses 800MHz frequency to operate because many cell phones are working on the same frequency. So I chose the sweeping oscillator as my VCO. It is really efficient yet may be difficult to use if you are beginner without some semi-professional RF-testing tools.

The clock oscillator (45MHz) is driving a local oscillator port as my noise source and is located on the mixer of the mini circuit. To equate the impedance of a clock oscillator with the mixer there is an impedance matching network. Local oscillator signal goes through this network and impedance is matched.

The 800MHz antenna from the old cell phone is connected to the RF input (mixer port). The RF output then goes to the amplifier located on the mini circuit. The amplifier will increase produced output by 15-16dbm of pure power. The empowered signal is going to another old phone antenna.

Step 2: Your Jammer Works!

GSM800 cell phones have their frequencies separated by 45MHz exactly. So when any cell phone tries to make a call - it becomes blocked by itself! The phone talker will hear its own voice.

You can also keep in mind that this cell phone signal jammer can block all cell-based trackers which use your car GPS to track you down and record the data. Even IEDs are probably could be jammed, at least those ones controlled by cell signals.

Step 3: Pics and Notes

I used 600MHz mixer but it works nice due to some electronic interferences.
The amplifier is really a must for this device even considering its power consumption.
The case is made from aluminium box for better heat loss.
UHF connectors were attached to the mini circuit because they are perfect for antennas to fasten.
Voltage regulator is required for the nine volts battery to convert voltage.
The battery located inside and separated from other details using foamed plastic.
Do not forget to place the power switch (it may seem obvious yet it is easy to forget).
The antennas from my old Motorola cell phone but you can use other models.

Well, this is probably all. Now go and make some cool stuff!