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Mobile Phone jammer circuit diagram


What is Mobile/Cell Phone Jammer

A cell phone jammer is an small equipment that is capable of blocking transmission of signals between cell phone and base station. This is mostly done by creating interference at the operating frequency ranges of cell phones, which results in no signal or significant loss of signal quality. Although cell phone jammers could be used practically anywhere, they are mainly used in areas where silence is expected or required, or that areas which required prohibited to use of mobile phone.

You Can Also Say Mobile Phone Signal Blocker

Mobile Phone Jammer blocks both Receiving and Transmitting signal.

• Cell phones use unique frequencies for talking and listening. Most cell phone jammers block either of the two frequencies, indirectly providing the effect of prevention of both. Cell phone jammers work on the same principles as that of jammers used in preventing radio communication. They either function by disrupting the cell-phone-to-base-station frequencies or base-station-to-cell-phone frequencies.

• It is efficient in blocking transmission of signals from networks including UMTS, 3G, CDMA, GSM and PHS.

• One Jammer device may not work at different frequencies , because Mobile phones operate at different frequency bands in different countries.   Also read Mobile Phone Detector Circuit

Working of jammer circuit

 Block Diagram of Mobile jammer


For any jammer circuit, there are 5 main important circuits. When they are combined together, the output of that circuit will work as a jammer. The main circuits are

• Power Supply 

• Voltage controlled Oscillator.

• Noise Pulse Generator

• RF Amplifier .

• Tranmitting Antenna

The RF amplifier circuit is created by the  transistor Q1, capacitors C4 & C5 and resistor R1. This will amplify the signal generated by the tuned circuit. The amplification signal is given to the antenna through C6 capacitor. Capacitor C6 will remove the DC and allow only the AC signal which is transmitted in the air.

Circuit Diagram

Here Capacitor C1 and Inductor L1 Works as frequency generator and oscillation, and Transistor is used for Amplification.

• You can Use the formula to change the frequency of circuit output depending on the frequencies you need to block, the values of inductor (L1) and capacitor (C1) can be altered as required.

For example, if mobile phones at your area work at 450 MHz, you need to generate 450 MHz with some noise to act as the blocking signal. Now the cell phone receiver will not be able to understand, which signal to receive. We have successfully blocked cell phone signals.

•  Capacitor C1 and inductor L1 a make a tuned circuit . This circuit  acts as an oscillator with zero resistance. It produces very high frequency with minimum damping. both inductor and capacitor of tuned circuit will oscillate at its resonating frequency. When transistor Q1 is turned ON, the tuned circuit at the collector turns ON.

•  The tuned circuit operation When the circuit is ON, voltage is stored in the capacitor. After completely charged of capacitor, it allows to flow the Charge (current) through the inductor. When current flows through the inductor, it stores magnetic energy corresponding to the voltage across the capacitor. When the charge of inductor reaches its maximum then the charge or voltage across the capacitor turns to Zero.

•  The magnetic charge through the inductor will decreased and the current will charge the capacitor in opposite or reverse polarity manner. Again after some period of time, capacitor will get completely charged and magnetic energy across the inductor will be completely zero. Again the capacitor will give charge to the inductor and becomes zero. After some time, inductor will give charge to capacitor and become zero and they will oscillate and generate the frequency. This process runs till internal resistance is generated and the oscillations stop.

•  The capacitors C2 and C3 generate noise pulses at the tuned circuit in randomly The RF amplifier boosts the frequency generated by the tuned circuit. The frequency generated by the tuned circuit and the noise signal generated by the capacitors C2 and C3 is combined, amplified and transmitted.

Power supply should between 3v to 5v. less than or upto 500ma 

⇒  This circuit works at small area , upto 100 meter , If the circuit is not working, just increase the resistor and capacitors values in the circuit. Increase the frequency of tuned circuit by using the formula which is given in this article.

Please Don not Use This For Unnecessary. It may illegal


Must Read Stereo FM Transmitter Circuit


About the Author


Hi, My name is Aman Bharti, I am interested in making and study of Electronics, circuit diagram, PCB designing and layout etc. I like to share the knowledge and all ideas with people which I get from My Experiment & from different sources. I try to provide any circuit details deeply with test results as possible. If you want to give a suggestion or comments on anything, please leave your comment in the comment box of the related page.

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