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July 5, 2022

How To Make Portable Cell Phone Jammer?

What is Portable Cell Phone Jammer?

Portable Cell Phone Jammer is a type of handheld signal jammer, usually about the size of a walkie-talkie. It blocks the communication signal of the corresponding device by sending interfering signals. Very useful in some special occasions.

For example, during school exams, signal jammers can block the communication signals in the exam room to prevent students from cheating.In war-torn countries, remote-controlled bombs are detonated via cell phone signals, and signal jammers can also be used to reduce casualties.

How To Make Portable Cell Phone Jammer?

The use of different frequencies makes it difficult to have a jammer for all frequencies. However, the below mentioned formula can be used to calculate the required values.

F= 1/ (2*pi*sqrt (L1*C1))

Depending on the frequencies you need to block, the values of the inductor (L1) and capacitor (C1) can be altered.

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.

Here, 450MHz is the tuning frequency. Cell phone jammers for other frequency ranges are designed similarly. However, the signal range is very weak. Thus, this circuit works only for a range of 100 m.

Cell Phone Jammer Circuit


For any jammer circuit, it’s essential to have three important subcircuits.

  • RF amplifier
  • Voltage Controlled Oscillator
  • Tuning circuit

These 3 circuits, when combined together form an efficient cell phone jammer circuit.


  • RF amplifier circuit comprises of the transistor Q1, capacitors C4, C5 and resistor R1. This RF circuit amplifies the signal generated by the tuned circuit. The amplified signal is given to the antenna through capacitor C6. It blocks DC and allows only the AC component of the signal to be transmitted.
  • When transistor Q1 is turned ON, the tuned circuit at the collector turns ON. The tuned circuit consists of capacitor C1 and inductor L1. This acts as an oscillator with zero resistance. It produces very high frequency with minimum damping.
  • When the circuit is ON, voltage is stored in the capacitor. Once the capacitor is completely charged, it allows charge to flow through the inductor. When current flows through the inductor, it stores magnetic energy corresponding to the voltage across the capacitor. At a certain point, the inductor reaches its maximum and the charge or voltage across the capacitor turns to zero.
  • Now the magnetic charge through the inductor decreases and the current charges the capacitor in opposite or reverse polarity. The process repeats and after a while, inductor charges the capacitor and becomes zero.
  • This process runs till internal resistance is generated and the oscillations stop. RF amplifier feed is given through capacitor C5 to the collector terminal before C6. The capacitors C2 and C3 generate pulses in a random fashion (noise) at the frequency generated by the tuned circuit.
  • 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.

Components Required

Resistor R1 Emitter Loading
Resistor R2 Base Biasing
Capacitor C1 Frequency Generation
Capacitor C2 Feedback
Capacitor C3 Feedback
Capacitor C4 Noise Reduction
Capacitor C5 Coupling
Capacitor C6 Coupling
Capacitor C7 Decoupling
Transistor Q1 Amplification
Inductor L1 Frequency Generation


  • This circuit can block signals only within a 100 meter radius.
  • Usage of this type of circuits is banned and illegal in most countries.
  • This circuit is also used in TV transmission and remote controlled toys.
  • If the circuit is not working properly, try increasing resistor and capacitors values in the circuit. Use the formula

F= 1/ (2*pi*sqrt (L*C)).

  • Power supply for the circuit should not exceed 3 Volts.



The production of a cell phone signal jammer is more complicated and requires professional knowledge, so it is a better way to buy a portable cell phone jammer. JAMST provides global delivery services.

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