A cell phone jammer is an electronic device that blocks signal transmission between a cell phone and a cell tower. By using the same frequencies as cell phones, signal jammers can cause strong interference with communications between callers and receivers. Can effectively block signal transmission from networks such as UMTS, 3G, CDMA, GSM and PHS.

DIY Cell Phone Jammer - Components Required

For any jammer circuit, there must be three important sub-circuits:

• RF amplifier


• Voltage Controlled Oscillator


• Tuning circuit

These 3 circuits combine to form an efficient cell phone jammer circuit.

Cell phone signal jammer working

1. Within the RF amplifier circuit, there is transistor Q1, as well as capacitors C4 and C5, and resistor R1. This particular circuit serves the purpose of amplifying the signal that is generated by the tuned circuit. Once amplified, the signal is then sent to the antenna through capacitor C6. By doing so, capacitor C6 prevents the transmission of any DC current, allowing only the AC component of the signal to pass through.


2. The turning on of transistor Q1 triggers the activation of the tuned circuit located at the collector. Comprised of capacitor C1 and inductor L1, this circuit operates as a zero resistance oscillator, producing exceptionally high frequencies with minimal damping.


3. As time progresses, the magnetic charge passing through the inductor decreases, resulting in the capacitor being charged in the opposite or reverse polarity. This sequence is repeated, and eventually, the inductor charges the capacitor until it reaches a neutral state.


4. The cessation of oscillation occurs when internal resistance is established, signifying the continuation of this process. Before reaching the collector terminal, the RF amplifier feed is directed through capacitor C5, followed by C6. Capacitors C2 and C3 generate random pulses (noise) at the frequency generated by the tuned circuit.


5. The frequencies generated by tuned circuits are amplified using RF amplifiers. These amplifiers combine and amplify the frequency produced by the tuned circuit with the noise signal generated by capacitors C2 and C3 before transmitting it.