Nowadays, the rapid development of cell-phones has raised a lot of problems. In addition, public response was rising against the difficulty of cell phones introduced in daily life. Here is a simple project that is “hidden active cell phone detector”. The cell phone detector is a pocket sized which can be used to detect the hidden active cell phone. So the proposed system is used to ignore the use of cell phones in some of the public places like exam halls, defense establishments, private rooms, military camp, hospitals, petrol pumps and also very useful for detecting the use of mobile phone for intelligence work and other correlated activities. This system can detect SMS, calls, video transmission even when the cell phone is secreted in silent mode. The quick bug detects RF (radio frequency) transmission signal from a cell phone, it produces a beep sound alarm.
Hidden Active Cell Phone Detector
The hardware requirements of a hidden active cell phone detector mainly include op-amp, 555 timer, transistor, led, resistors, capacitors, piezo buzzer, switch, battery, and antenna.
- The combination of hardware and software, which can form a component of a larger machine
- An example of an embedded system is a microprocessor that controls an automobile engine.
- An embedded system is designed to run on its own without human intervention, and may be required to respond to events in real time.
The 555 Timer IC is an integrated circuit (chip) implementing a variety of timer and multivibrator applications.The 555 has three operating modes:
Monostable Mode: in this mode, the 555 functions as a “one-shot”. Applications include timers, missing pulse detection, switches, touch switches, frequency divider, capacitance measurement, pulse-width modulation (PWM) etc.
Astable – free running mode: the 555 can operate as an oscillator. Uses include LED and lamp flashers, pulse generation, logic clocks, tone generation, security alarms, pulse position modulation, etc.
Bistable Mode or Schmitt Trigger: the 555 can operate as a flip-flop, if the DIS pin is not connected and no capacitor is used. Uses include bounce free latched switches, etc.
LM358 (Dual Operational Amplifier)
The LM358 series consists of two independent, high gain; internally frequency compensated operational amplifiers which were designed specifically to operate from a single power supply over a wide range of voltages
Operation from split power supplies is also possible and the low power supply current drain is independent of the magnitude of the power supply voltage.
- Pin-1: Output 1
- Pin-2: Inverting input
- Pin-3: Non-inverting input
- Pin-4: VCC-
- Pin-5: Non-inverting input 2
- Pin-6: Inverting input 2
- Pin-7: Output 2
- Pin-8: VCC+
- The LM339 consists of four independent precision voltage comparators
- The LM339 series was designed to directly interface with TTL and CMOS.
- When operated from both plus and minus power supplies, the LM339 series will directly interface with MOS logic where their low power drain is a distinct advantage over standard comparators.
- Wide single supply voltage range 2.0VDC TO 36VDC or dural supplies ±1.0VDC to ±18VDC
- Very low supply current drain (0.8㎃) independent of supply voltage (1.0㎽/comparator at 5.0VDC)
- Low input biasing current 25㎁
- Low input offset current ±5㎁ and offset voltage
- Input common-mode voltage range includes ground
- Differential input voltage range equal to the power supply voltage
- Low output 250㎷ at 4㎃ saturation voltage
- Output voltage compatible with TTL, DTL, ECL, MOS and CMOS logic system
- Moisture Sensitivity Level 3
BC547 (NPN –Transistor)
- The BC547 transistor is an NPN Epitaxial Silicon Transistor.
- It is used in general-purpose switching and amplification BC847/BC547 series 45 V, 100 mA NPN general-purpose transistors.
- The ratio of two currents (Ic/Ib) is called the DC Current Gain of the device and is given the symbol of hfe or nowadays Beta, (β).
- A buzzer or beeper is an audio signaling device, which may be mechanical or electromechanical piezoelectric.
- A piezoelectric element may be driven by an oscillating electronic circuit or other audio signal source, driven with a piezoelectric audio amplifier.
- An electrical battery is a combination of one or more electrochemical cells, used to convert stored chemical energy into electrical energy.
- The battery has become a common power source for many household, robotics and industrial applications.
- Larger batteries provide standby power for telephone exchanges or computer data centers
The main scope of project is to sense the presence of an activated mobile phone from a distance of one-and-a-half meters to prevent the use of same in the examination halls. In this project an RF detector using tuned LC circuits is formed for detecting signals in the GHz frequency band used in mobile phones as the transmission frequency of mobile phone ranges from 0.9 to 3 GHz. When the mobile phone is activated the RF transmission signal is detected by the detector and starts sounding a beep alarm and the LED blinks.
This is all about “hidden active cell phone detector circuit & it’s working”, the applications of this system mainly include where the utilize of cell phone is prohibited like gas station, petrol pumps, historical places, court of laws, religious places, examination halls, theatres, spying and military bases, unauthorized video transmission, hospitals, conferences and embassies. We hope that you have got a better understanding of this concept. Furthermore, any doubt regarding this concept, or to implement hidden active cell phone detector please give your feedback in the comment section below. Here is a question for you, What are the advantages of cell phone detector?