Mobile Phone Circuit Diagrams

# 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 Jammer Circuit.

### Outline

• Introduction
• Circuit 1: Mobile Jammer Circuit using 555
• Components Required
• Operation
• Circuit 2: Simple Mobile Jammer Circuit Diagram
• Cell Phone Jammer Circuit Explanation

## Introduction

A Mobile Jammer Circuit, alternatively referred to as a Cell Phone Jammer Circuit, is a device designed to prevent mobile phones from receiving signals. It operates as an RF transmitter that emits radio signals within the same or a similar frequency range as GSM communication.

CAUTION: Blocking or interfering with radio signals is typically illegal in many countries. Prior to employing such devices, it is essential to familiarize yourself with the regulations applicable in your region.

In this undertaking, I have constructed two Mobile Jammer Circuits. One of them utilizes a 555 Timer IC, while the other incorporates a combination of active and passive components.

## Circuit 1: Mobile Jammer Circuit using 555

#### 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

## Operation

After assembling the circuit on a perf board, I positioned a cell phone nearby and connected power to it (though I haven’t activated the switch yet). Initially, my phone displayed strong signal reception with full bars.

However, as soon as I activated the circuit, the signal bars on my phone started to weaken gradually, eventually reducing to just a single bar.

Based on this observation, it can be deduced that the circuit has the ability to attenuate signals but does not completely block them.

## Cell Phone Jammer Circuit Explanation

If you comprehend the preceding circuit, the analysis of this circuit is straightforward and uncomplicated. In the case of any jammer circuit, it is essential to bear in mind that there are three primary circuits of significance. When these three circuits are integrated, the resulting output of the circuit functions as a jammer. These three pivotal circuits are:

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

The RF amplifier circuit comprises components such as transistor Q1, capacitors C4 and C5, and resistor R1. Its role is to amplify the signal generated by the tuned circuit. The amplified signal is then transmitted to the antenna via capacitor C6, which serves to filter out the DC signal, permitting only the AC signal to be broadcast.

At the collector, the tuned circuit is activated when transistor Q1 is turned on. This tuned circuit consists of capacitor C1 and inductor L1 and functions as a zero-resistance oscillator. It generates a high-frequency signal with minimal damping, as both the inductor and capacitor in the tuned circuit oscillate concurrently.

The operation of the tuned circuit is fairly straightforward. When the circuit is powered on, the capacitor stores voltage based on its capacity. Capacitors primarily store electrical energy. As the capacitor reaches full charge, the charge flows through the inductor, which stores magnetic energy. The voltage across the capacitor gradually diminishes until the inductor has absorbed all the magnetic energy, causing the voltage across the capacitor to drop to zero.

Subsequently, the magnetic charge in the inductor diminishes, and the capacitor starts charging in the opposite or reverse polarity. After a certain period, the capacitor attains full charge, and the magnetic energy in the inductor returns to zero. This cycle repeats, causing the inductor and capacitor to oscillate and generate the desired frequency.

If this cycle continues until it encounters internal resistance, the oscillations cease. The RF amplifier feed is directed to the collector terminal before C6 to enhance the signal sent to the tuned circuit. Capacitors C2 and C3 introduce noise into the frequency generated by the tuned circuit. These capacitors, technically referred to as noise generators, produce random electrical pulses.

The feedback or amplification from the RF amplifier, the tuned circuit’s frequency, and the noise signal generated by capacitors C2 and C3 are all combined, amplified, and transmitted into the air.

To block a cell phone operating at 450 MHz, a 450 MHz frequency with added noise is generated. This serves as a basic blocking signal, causing the mobile phone receiver to be uncertain about the signal it’s receiving. Consequently, this circuit prevents cell phone signals from reaching the phones.

In summary, the circuit outlined above functions as a jammer by generating the 450 MHz frequency to disrupt the actual cell phone signal.

### Note:

• This circuit has an effective range of approximately 100 meters, meaning it can disrupt cell phone signals within a radius of 100 meters.

• It’s important to note that the use of such circuits is prohibited in most countries, and employing this circuit is illegal. If you are caught using this circuit, you may face imprisonment and substantial fines as penalties.

• This circuit has applications beyond signal jamming; it can also be employed in TV transmission and for powering remote-controlled toys or devices.

• If the circuit isn’t functioning as intended, you can enhance its performance by increasing the values of the resistors and capacitors. To adjust the frequency of the tuned circuit, you can utilize the formula F = 1 / (2 * π * sqrt(L * C)). Increasing the values of the components in the inductor-capacitor circuit will result in a higher frequency.

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