I guess you are happy now in the same way as I was happy not so long ago. You see, I was in the same situation as you do. Many months were spent in violent efforts looking for schemes and instructions. But now all those sleepless nights are gone and it happened thanks to Jammer Store Inc. and their skilled manufacturing team.

Their marvelous blog post is the one you may call life-saving. For me it was like a draught of water in a dry wasteland. Using their instructions I have managed to build my own cell phone jammer, at last! And now you can do the same.

Working Principles. This cell phone jammer operates at GSM800 frequency since most mobile phones use it to operate. So the selected VCO is a sweeping oscillator, which is very effective but may be hard to construct for the beginners without nice RF-testing equipment.
As a noise source you can use 45MHz clock oscillator which is driving Local Oscillator port located on a mini-circuit mixer. There is also an impedance matching network for Local Oscillator signal to pass through it. It is used to equate impedances of the clock oscillator and the port of the mixer.
RF input (which is this port of the mixer) connected to the first 800MHz cell phone antenna, and the RF output is sent to the mini-circuit amplifier. This amplifier increases the output power for 15-16dbm. The amplified signal then sent to the second cell phone antenna.

How It Works? All cell phones which use GSM800 have their transmitted and received frequencies always separated by 45MHz. So when the mobile phone tries to call it is blocked by its own signal returning to it! Isn’t that cool? When the phone blabber annoys you – turn your jammer on and that wrongdoer will hear own voice in his or her cell phone.
Oh, by the way, you can also use this mobile signal jammer to block any cell-based tracking systems which use your GPS to track and record your car’s moves. And it is quite possible (though I didn’t actually tested it) to jam IEDs which detonated using cell phones.

Pics And Notes. The mixer I used is designed to work up to 600MHz but in this case it works pretty well. RF amplifier is doing its job perfectly yet (as it was mentioned in the Jammer Store blog post) draws additional power.
Old aluminium box was used as a frame for the jammer and old UHF connectors from Motorola cell phone as input/output.

You need to attach RF connectors to the circuit. Nine volt battery and voltage regulator were used to supply all components. The battery was placed inside and separated by the foamed plastic from the other components. The power on/off switch is placed on the top. The input and output antennas (also from old Motorola mobile phone) are screwed onto UHF connectors. Your cell phone jammer is ready. Enjoy it anywhere and anywhen.