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Mobile Jammer Circuit

In the earlier post, we have studied about Simple FM Radio Jammer Circuit and its applications. Now, let us learn about one more interesting concept i.e. Cell Phone or Mobile Phone Jammer Circuit.


A Mobile Jammer Circuit or a Cell Phone Jammer Circuit is an instrument or device that can prevent the reception of signals by Mobile Phones. Basically, a Mobile Jammer Circuit is an RF Transmitter, which broadcasts Radio Signals in the same (or similar) frequency range of the GSM Communication.

WARNING: Blocking or Jamming Radio Signals is illegal in most countries. Check your local laws before using such devices.

In this project, I have designed two Mobile Jammer Circuits, where the first one is using a 555 Timer IC and the other one is built using active and passive components.  

Circuit 1: Mobile Jammer Circuit using 555

Mobile Jammer Circuit Diagram

Components Required

  • 555 Timer IC
  • Resistors – 220Ω x 2, 5.6KΩ, 6.8KΩ, 10KΩ, 82KΩ
  • Capacitors – 2pF, 3.3pF, 4.7pF, 47pF, 0.1µF, 4.7µF, 47µF
  • 30pF Trimmer Capacitor
  • LED
  • Coils 3 Turn 24 AWG, 4 Turn 24 AWG
  • Antenna 15 Turn 24 AWG
  • BF495 Transistor
  • ON / OFF Switch
  • 9V Battery


After building this circuit on a perf board and supplying power to it, I have placed a mobile phone near the circuit (I am yet to turn on the switch). Before turning on the power, my mobile phone was able to capture majority of the signals as it is displaying full bars.

Once I turned on the circuit, the signal bars on the phone started to reduce and finally it stopped at a single bar.

So, in conclusion, I can say that this circuit blocks the signals but cannot completely jam them.

Mobile Jammer Circuit Image 1


Circuit 2: Simple Mobile Jammer Circuit Diagram

Mobile Jammer Circuit Diagram
Simple Mobile Jammer Circuit Diagram

Cell Phone Jammer Circuit Explanation

If you understand the above circuit, this circuit analysis is simple and easy. For any jammer circuit, remember that there are three main important circuits. When they are combined together, the output of that circuit will work as a jammer. The three circuits are

  • RF amplifier.
  • Voltage controlled oscillator.
  • Tuning circuit.

So the transistor Q1, capacitors C4 & C5 and resistor R1 constitute the RF amplifier circuit. 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.

When the transistor Q1 is turned ON, the tuned circuit at the collector will get turned ON. The tuned circuit consists of capacitor C1 and inductor L1. This tuned circuit will act as an oscillator with zero resistance.

This oscillator or tuned circuit will produce the very high frequency with minimum damping. The both inductor and capacitor of tuned circuit will oscillate at its resonating frequency.

The tuned circuit operation is very simple and easy to understand. When the circuit gets ON, the voltage is stored by the capacitor according to its capacity. The main function of capacitor is to store electric energy. Once the capacitor is completely charged, it will allow the charge to flow through inductor. We know that inductor is used to store magnetic energy. When the current is flowing across the inductor, it will store the magnetic energy by this voltage across the capacitor and will get decreased, at some point complete magnetic energy is stored by inductor and the charge or voltage across the capacitor will be 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 circle run upto the internal resistance is generated and oscillations will get stop. RF amplifier feed is given through the capacitor C5 to the collector terminal before C6 for gain or like a boost signal to the tuned circuit signal. The capacitors C2 and C3 are used for generating the noise for the frequency generated by the tuned circuit. Capacitors C2 and C3 will generate the electronic pulses in some random fashion (technically called noise).

The feedback back or boost given by the RF amplifier, frequency generated by the tuned circuit, the noise signal generated by the capacitors C2 and C3 will be combined, amplified and transmitted to the air.

Cell phone works at the frequency of 450 MHz frequency. To block this 450MHz frequency, we also need to generate 450Mhz frequency with some noise which will act as simple blocking signal, because cell phone receiver will not be able to understand to which signal it has been received. By this, we can able to block the cell phone signal from reaching the cell phones.

So here in the above circuit, we generated the 450 MHz frequency to block the actual cell phone signal. That’s what the above circuit will act as a jammer for blocking the actual signal.

You can also get good idea about another jammer circuit i.e. How TV Remote Control Jammer Circuit Works?


  • This circuit will work in the range of 100 meters i.e. it can block the signals of cell phones with in 100 meters radius.
  • Usage of this type of circuits is banned in most of the countries. Usage of this circuit is illegal and if you caught by using this circuit, you can be imprisoned and also should pay large amount in the form of fine.
  • This circuit can be used in TV transmission and also for remote controlled toys or play things.
  • If the circuit is not working, just increase the resistor and capacitors values in the circuit. Increase the frequency of tuned circuit by using this formula F= 1/ (2*pi*sqrt (L*C)). Increase the inductor capacitor circuit components value for increasing the frequency.

Know How To Make an Adjustable Timer 

148 Responses

  1. Good post,thanks for the author sharing the news about the cell phone jammer,from my point of view ,the cell phone jammer will be become more and more popular.

  2. Im interested in building this circuit for a project and I wanted to know where can i get all the parts to build it. Are there any kits that give you all the components?

    1. for all its depend on you which type of antenna u have to use because the antenna will transmit or receive the signal which is the output/input of your circuit. so you are engineer or google it and check the output of you circuit and by using Dipole length formula (antenna length )
      Length (meters) = 150 x A / frequency in MHz
      Length (inches) = 5905 x A / frequency in MHz
      there are many type of antenna and the work same as it but they have some feature example
      Radio antenna (mono pole antenna)= it transmit and receive signal from 360 degree
      but if u use YAGI UDDA antenna it transmit and recevie the signal from one direction there fore in old time u people use this antenna and rotate them to take a single and best signal from one direction for more please google it u can get more knowledge from there.

  3. i am also really intrested in this jammer but i am still confued about the component. so can you please give me the part list of this circuit ?

  4. sir we are trying to make this circuit as our project in university. but it is not working properly although the circuit is completely according to the give circuit. please guide us about any specifications about that circuit. please reply as soon as possible

      1. Your circuit produces noise of frequency 450MHz, whereas most of the countries use 900~1800MHz bands for GSM communication. Can you help me out with the corresponding component values for the same?

      2. you might want to do a little more research….the last time i checked the cell phone frequencies world over are around 800/1800/1900mhz so jamming 450 will do didly squat to cell phones but it will seriously piss of radio amateurs in the 70cm band.

    1. Sir, i have been trying the same design, but we are unable to generate the spectra. In fact our transistor is not getting biased. please help me

  5. We want to do this project but are there any legal issues of implementing this project?

    And we would like to reduce the distance area of the circuit from 100m to around 6-9m.. How to do that? Plz reply asap to my mail id

  6. as you are saying.. sir…that if it doesn’t work properly..just increase the..value of capacitor..and resistor…but there are…many capacitors..which one we should..increase the value… please reply soon

  7. I’ve made this circuit and it doesn’t worked at all! I checked the values of every component twice but still it doesn’t work!

  8. Sir, I rigged up the circuit but it is not working. I have taken this as my project. I desperately need your help. Please help me. Please reply as soon as possible

  9. sir,
    please confirm me weather all the capaciters are ceramic one or electrolytic or its a mixture of both. if its a mixture tell me according to tha capaciter numbering,

  10. Hello
    really this circuit can work?
    im in iran can i use that?
    i heard this circuit work on :Mobile jammer circuit use only in GSM1900 with frequency from 1930 MHz – 1990 MHz. The GSM1900 mobile phone network is used USA, Canada
    and in your opinion can i use BF 495?
    i cant find BF 494

  11. In my country a branded mobile phone operates on GSM 900/1800 MHz standard and operates on allocated 12.8 MHz frequency spectrum.Can i use this circuit?If any modification or changes required please mention them.

  12. Sir,I have the problem with simulation of the given circuit on multisim….There is no generation of frequency and only gives the DC values….Values of the components are same as shown in circuit…

  13. I tried creating the circuit. Unfortunately as predicted, the circuit didn’t work. Please if you could let me know 2 things regarding this circuit, with which I should be able to tweak and get it worked:
    1. Whether any micro/onboard/simple antenna (unlike the Yagi Uda) works with the circuit.
    2. Values for which components could be changed to reach a higher frequency.

  14. Can you please explain how you obtained the values of the components such as the capacitors and resistors in the circuit
    And the formualae for the amplifier
    And all the other design parameters

  15. I am going to use SMD and thru Hole components, I need help in this.

    Since no package details/footprint is given, i cannot execute this circuit

  16. Signal is generated by tuning circuit, what is the role of antenna.
    I mean how it will affect the purpose of the circuit.

  17. HI,

    What is the job of antenna, the signal is generated by the tuning circuit. I mean how it affects the purpose of the circuit.


  18. Sir, I am working on the project which has to block the particualr frequency say reliance or Idea in GSM Can I do such a project??

  19. I now have understanding of frequency jamming. I’ve calculated the value of the Inductor and Capacitor to give a resonant frequency of 450MHz. I can now build it. Thanks to the Author.

  20. please i am from nigeria..i want to know how many number of turns and swg of the conductor.and cross sectonal area.for the 22nh doing it as my me pleas

    1. did it finally work? and are there major changes you made to the circuit or did u use the one given ?
      kindly assist me make one

  21. “If the circuit is not working, just increase the resistor and capacitors values in the circuit. Increase the frequency of tuned circuit by using this formula F= 1/ (2*pi*sqrt (L*C)).
    Increase the inductor capacitor circuit components value for increasing the frequency.”

    Yet running F= 1/ (2*pi*sqrt (L*C)) in this schematic (tuning circuit) yields a frequency of 277053.19427199627 Hz (0.27705319427199626 MHz)…..not 450Mhz, nor GSM1900 with frequency from 1930 MHz – 1990 MHz.

    To get close to 450 MHz you need a combo like 21pf & 6nH, or 1pf & 125nH)
    To get close to the 1930-1990 range you need 3pf & 2nH or 13pf & .5nH or 36pf & .2nH, etc.).

    1. I’m no circuitician, but it seem, as above, if you used a 200pH inductor (aka .2nH) you could then use a tunable cap, with a range of max 35pf (1902.265MHz) to min 31pf (2021.269 MHz) to sweep & cover the full range of 1930-1990MHz.

  22. May i know the inductor specifications which is used in jammer circuit or else could you please send me a link to buy that inductor.i don’t have much time please give reply as early as possible

  23. What is the spec’s of the inductor for this critical? Output depends on this plzz reply asap

  24. Dunno if folks are aware but using this thing in at least the United States is hardcore illegal and can get you in serious trouble with the FCC (or CISPR if you live in Europe). I say that as an electrical engineer who works in EMC, EMI, and RF testing for a living. Unless you like threats of large fines, be extremely careful where you use this if you live in the US.

  25. Is The Circuit Is Working Really I want Make This For My Mini Project If There Is Problem in This Circuit Then What We Do …. Any Suggestion Please

  26. Hello would it be possible to add something to circuit #2 so the range of the circuit can be adjusted rather than fixed at 100m? If so, could you please let me know how I could design the circuit so that I can adjust the range?

  27. I’m very happy for more enlighten about signal jammer. Thanks a lot. But I want you people to guide me

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