GSM Detector

1.Introduction:-

This handy mobile bug or cell phone detector, pocket-size mobile transmission detector or sniffer

can sense the presence of an activated mobile cellphone from a distance of one and-a-half

metres.

So it can be used to prevent use of mobile phones in examination halls, confidential rooms, etc. It

is also useful for detecting the use of mobile phone for spying and unauthorised video

transmission.

The circuit can detect both the incoming and outgoing calls, SMS and video transmission even if

the mobile phone is kept in the silent mode.

The moment the bug detects RF transmission signal from an activated mobile phone, it starts

sounding a beep alarm and the LED blinks. The alarm continues until the signal transmission

ceases.

This is a mobile phone sniffer circuit that can detect the signals being used in the GSM (Global

System for Mobile Communication) band at about 900 MHz. Since the signals are digitally

encoded, it can detect only the signal activity, not the speech or the message contents. A

headphone is used to hear the detected signals.

Every detector unit consists of a dipole antenna, a choke and a diode. The antenna receives the

GSM signals in media. Then a small amount of charge is induced in the choke. The diode

demodulates the signal and finishes detecting. The diodes must be schottky diodes or germanium

diodes. Since the forward voltage of a silisium diode is high, it won’t give a sufficient result in

this circuit.

1

Circuit Diagram:-

Fig 1

2.Procedure:-

An ordinary RF detector using tuned LC circuits is not suitable for detecting signals in the GHz

frequency band used in mobile phones. The transmission frequency of mobile phones ranges

from 0.9 to 3 GHz with a wavelength of 3.3 to 10 cm. So a circuit detecting gigahertz signals is

required for a mobile bug.

Here the circuit uses a 0.22μF disk capacitor (C3) to capture the RF signals from the mobile

phone. The lead length of the capacitor is fixed as 18 mm with a spacing of 8 mm between the

leads to get the desired frequency. The disk capacitor along with the leads acts as a small

gigahertz loop antenna to collect the RF signals from the mobile phone.

Op-amp IC CA3130 (IC1) is used in the circuit as a current-to-voltage converter with capacitor

C3 connected between its inverting and non-inverting inputs. It is a CMOS version using gate-

protected p-channel MOSFET transistors in the input to provide very high input impedance, very

2

low input current and very high speed of performance. The output CMOS transistor is capable of

swinging the output voltage to within 10 mV of either supply voltage terminal.

Capacitor C3 in conjunction with the lead inductance acts as a transmission line that intercepts

the signals from the mobile phone. This capacitor creates a field, stores energy and transfers the

stored energy in the form of minute current to the inputs of IC1. This will upset the balanced

input of IC1 and convert the current into the corresponding output voltage.

Capacitor C4 along with high-value resistor R1 keeps the non-inverting input stable for easy

swing of the output to high state. Resistor R2 provides the discharge path for capacitor C4.

Feedback resistor R3 makes the inverting input high when the output becomes high. Capacitor

C5 (47pF) is connected across ‘strobe’ (pin 8) and ‘null’ inputs (pin 1) of IC1 for phase

compensation and gain control to optimise the frequency response.

When the cell phone detector signal is detected by C3, the output of IC1 becomes high and low

alternately according to the frequency of the signal as indicated by LED1. This triggers

monostable timer IC2 through capacitor C7. Capacitor C6 maintains the base bias of transistor

T1 for fast switching action. The low-value timing components R6 and C9 produce very short

time delay to avoid audio nuisance.

Assemble the cell phone detector circuit on a general purpose PCB as compact as possible and

enclose in a small box like junk mobile case. As mentioned earlier, capacitor C3 should have a

lead length of 18 mm with lead spacing of 8 mm. Carefully solder the capacitor in standing

position with equal spacing of the leads. The response can be optimised by trimming the lead

length of C3 for the desired frequency. You may use a short telescopic type antenna.

Use the miniature 12V battery of a remote control and a small buzzer to make the gadget pocket-

size. The unit will give the warning indication if someone uses mobile phone within a radius of

1.5 meters.

3

3. 555 Timer IC

3.1)Introduction:-

The 555 timer IC is an integrated circuit (chip) used in a variety of timer, pulse generation,

and oscillator applications. The 555 can be used to provide time delays, as an oscillator, and as

a flip-flop element. Derivatives provide up to four timing circuits in one package.

Introduced in 1972 by Signetics, the 555 is still in widespread use, thanks to its ease of use, low

price, and good stability. It is now made by many companies in the original bipolar and also in

low-power CMOS types. As of 2003, it was estimated that 1 billion units are manufactured every

year.

NE555 from Signetics in dual-in-line package:-

Fig 2.

4

Design:-

The IC was designed in 1971 by Hans R. Camenzind under contract to Signetics, which was later

acquired by Philips.

Depending on the manufacturer, the standard 555 package includes 25 transistors, 2 diodes and

15 resistors on a silicon chip installed in an 8-pin mini dual-in-line package (DIP-8).[2] Variants

available include the 556 (a 14-pin DIP combining two 555s on one chip), and the two 558 &

559s (both a 16-pin DIP combining four slightly modified 555s with DIS & THR connected

internally, and TR is falling edge sensitive instead of level sensitive). There is no 557.

The NE555 parts were commercial temperature range, 0 °C to +70 °C, and the SE555 part

number designated the military temperature range, −55 °C to +125 °C. These were available in

both high-reliability metal can (T package) and inexpensive epoxy plastic (V package) packages.

Thus the full part numbers were NE555V, NE555T, SE555V, and SE555T. It has been

hypothesized that the 555 got its name from the three 5 kΩ resistors used within,[3] but Hans

Camenzind has stated that the number was arbitrary.[1]

Low-power versions of the 555 are also available, such as the 7555 and CMOS TLC555. [4] The

7555 is designed to cause less supply noise than the classic 555 and the manufacturer claims that

it usually does not require a "control" capacitor and in many cases does not require a decoupling

capacitor on the power supply. Such a practice should nevertheless be avoided, because noise

produced by the timer or variation in power supply voltage might interfere with other parts of a

circuit or influence its threshold voltages.

5

The Design For 555 Timer IC:-

Fig 3

3.2) PINS:-

The connection of the pins for a DIP package is as follows:

Fig 4

Note-PIN 5 is also called control voltage pin! By applying a voltage to the CONTROL

VOLTAGE input, pin 5, you can alter the timing characteristics of the device. In most

applications, the CONTROL VOLTAGE input is not used. It is usual to connect a 10 nF

capacitor between pin 5 and 0 V to prevent interference. The CONTROL VOLTAGE input can

be used to build an astable with a frequency modulated output.

6

Pin Name Purpose

1 GND Ground, low level (0 V)

2 TRIG OUT rises, and interval starts, when this input falls below 1/2 of CTRL voltage.

3 OUT This output is driven to approximately 1.7V below +VCC or GND.

4 RESET

A timing interval may be reset by driving this input to GND, but the timing does not begin

again until RESET rises above approximately 0.7 volts. Overrides TRIG which overrides

THR.

5 CTRL "Control" access to the internal voltage divider (by default, 2/3 VCC).

6 THR The interval ends when the voltage at THR is greater than at CTRL.

7 DIS Open collector output; may discharge a capacitor between intervals. In phase with output.

8 VCC Positive supply voltage is usually between 3 and 15 V.

Table 1

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4.)Modes

The 555 has three operating modes:

4.1.Monostable mode: in this mode, the 555 functions as a "one-shot" pulse generator.

Applications include timers, missing pulse detection, bouncefree switches, touch switches,

frequency divider, capacitance measurement, pulse-width modulation (PWM) and so on.

4.2.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 and so on. The 555 can be used as a simple ADC, converting an analog value to a

pulse length. E.g. selecting a thermistor as timing resistor allows the use of the 555 in a

temperature sensor: the period of the output pulse is determined by the temperature. The use of a

microprocessor based circuit can then convert the pulse period to temperature, linearize it and

even provide calibration means.

4.3.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.

4.1)Monostable Mode:-

In the monostable mode, the 555 timer acts as a "one-shot" pulse generator. The pulse begins

when the 555 timer receives a signal at the trigger input that falls below a third of the voltage

supply. The width of the output pulse is determined by the time constant of an RC network,

which consists of a capacitor (C) and a resistor(R). The output pulse ends when the voltage on

the capacitor equals 2/3 of the supply voltage. The output pulse width can be lengthened or

shortened to the need of the specific application by adjusting the values of R and C.[5]

The output pulse width of time t, which is the time it takes to charge C to 2/3 of the supply

voltage, is given by

where t is in seconds, R is in ohms and C is in farads.

8

While using the timer IC in monostable mode, the main disadvantage is that the time span

between any two triggering pulses must be greater than the RC time constant.

Diagrams:-

Schematic Of 555 Monostable Mode

Relationship Of Trigger Signa

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4.2)Bistable Mode:-

In bistable mode, the 555 timer acts as a basic flip-flop. The trigger and reset inputs (pins 2 and 4

respectively on a 555) are held high via Pull-up resistors while the threshold input (pin 6) is

simply grounded. Thus configured, pulling the trigger momentarily to ground acts as a 'set' and

transitions the output pin (pin 3) to Vcc (high state). Pulling the reset input to ground acts as a

'reset' and transitions the output pin to ground (low state). No capacitors are required in a bistable

configuration. Pin 5 (control) is connected to ground via a small-value capacitor (usually 0.01 to

0.1 uF); pin 7 (discharge) is left floating.

Schematic of a 555 in bistable mode:-

Fig 6

4.3)Astable Mode:-

In astable mode, the 555 timer puts out a continuous stream of rectangular pulses having a

specified frequency. Resistor R1 is connected between VCCand the discharge pin (pin 7) and

another resistor (R2) is connected between the discharge pin (pin 7), and the trigger (pin 2) and

threshold (pin 6) pins that share a common node. Hence the capacitor is charged through R1 and

R2, and discharged only through R2, since pin 7 has low impedance to ground during output low

intervals of the cycle, therefore discharging the capacitor.

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In the astable mode, the frequency of the pulse stream depends on the values of R1, R2 and C:

[7]

The high time from each pulse is given by:

and the low time from each pulse is given by:

where R1 and R2 are the values of the resistors in ohms and C is the value of the capacitor

in farads.

The power capability of R1 must be greater than

.

Particularly with bipolar 555s, low values of R1 must be avoided so that the output stays

saturated near zero volts during discharge, as assumed by the above equation. Otherwise the

output low time will be greater than calculated above. It should be noted that the first cycle will

take appreciably longer than the calculated time, as the capacitor must charge from 0V to 2/3 of

VCC from power-up, but only from 1/3 of VCC to 2/3 of VCC on subsequent cycles.

o achieve a duty cycle of less than 50% a diode (that is fast enough for the application) can be

added in parallel with R2 towards the capacitor. This bypasses R2 during the high part of the

cycle so that the high interval depends approximately only on R1 and C. The presence of the

diode is a voltage drop that slows charging on the capacitor so that the high time is longer than

the often-cited ln(2)*R1C = 0.69 R1C. The low time is the same as without the diode as shown

above. With a diode, the high time is

where Vdiode is determined when the diode has a current of 1/2 of Vcc/R1. As an extreme example,

when Vcc= 5 and Vdiode= 0.7, high time = 1.00 R1C which is 45% longer than the "expected"

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0.693 R1C. At the other extreme, when Vcc= 15 and Vdiode= 0.3, high time = 0.725 R1C, 4.6%

longer. The equation reduces to 0.693 R1C if Vdiode= 0.

The operation of RESET in this mode is not well defined, some manufacturers' parts will hold

the output state to what it was when RESET is taken low, others will send the output either high

or low.

Standard 555 astable circuit:-

Fig 7

5.)Specifications:-

These specifications apply to the NE555. Other 555 timers can have different specifications

depending on the grade (military, medical, etc.).

Supply voltage (VCC) 4.5 to 15 V

Supply current (VCC = +5 V) 3 to 6 mA

Supply current (VCC = +15 V) 10 to 15 mA

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Output current (maximum) 200 mA

Maximum Power dissipation 600 mW

Power consumption (minimum

operating)30 mW@5V, 225 mW@15V

Operating temperature 0 to 70 °C

( Table 2)

556 Dual timer:-

The dual version is called 556. It features two complete 555s in a 14 pin DIL package.

558 Quad timer:-

The quad version is called 558 and has 16 pins. To fit four 555s into a 16 pin package the

control, voltage, and reset lines are shared by all four modules. Each module's discharge and

threshold are wired together internally and called timing.

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6.)Derivatives

Many pin-compatible variants, including CMOS versions, have been built by various companies.

Bigger packages also exist with two or four timers on the same chip. The 555 is also known

under the following type numbers:

Manufacturer Model Remark

Avago Technologies Av-555M

Custom Silicon Solutions[8] CSS555/CSS555C CMOS from 1.2 V, IDD < 5 µA

CEMI ULY7855

ECG Philips ECG955M

Exar XR-555

Fairchild Semiconductor NE555/KA555

Harris HA555

IK Semicon ILC555 CMOS from 2 V

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Intersil SE555/NE555

Intersil ICM7555 CMOS

Lithic Systems LC555

Maxim ICM7555 CMOS from 2 V

Motorola MC1455/MC1555

National SemiconductorLM1455/LM555/

LM555C

National Semiconductor LMC555 CMOS from 1.5 V

NTE Sylvania NTE955M

Raytheon RM555/RC555

RCA CA555/CA555C

STMicroelectronics NE555N/ K3T647

Texas Instruments SN52555/SN72555

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Texas Instruments TLC555 CMOS from 2 V

USSR K1006ВИ1

Zetex ZSCT1555 down to 0.9 V

NXP Semiconductors ICM7555 CMOS

HFO / East Germany B555

7.)Example Applications:-

1.)Joystick interface circuit using the 558 quad timer:-

The Apple II microcomputer used a quad timer 558 in monostable (or "one-shot") mode to

interface up to four "game paddles" or two joysticks to the host computer. It also used a single

555 for the cursor flashing.

A similar circuit was used in the IBM PC. In the joystick interface circuit of the IBM PC,

the capacitor (C) of the RC network (see Monostable Mode above) was generally a 10 nF

capacitor. Theresistor (R) of the RC network consisted of the potentiometer inside the joystick

along with an external resistor of 2.2 kilohms.[10] The joystick potentiometer acted as a variable

resistor. By moving the joystick, the resistance of the joystick increased from a small value up to

about 100 kilohms. The joystick operated at 5 V.

Software running in the host computer started the process of determining the joystick position by

writing to a special address (ISA bus I/O address 201h). This would result in a trigger signal to

the quad timer, which would cause the capacitor (C) of the RC network to begin charging and

cause the quad timer to output a pulse. The width of the pulse was determined by how long it

took the C to charge up to 2/3 of 5 V (or about 3.33 V), which was in turn determined by the

joystick position.

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Software running in the host computer measured the pulse width to determine the joystick

position. A wide pulse represented the full-right joystick position, for example, while a narrow

pulse represented the full-left joystick position.

2.)Atari Punk Console:-

One of Forrest M. Mims III's many books was dedicated to the 555 timer. In it, he first published

the "Stepped Tone Generator" circuit which has been adopted as a popular circuit, known as

theAtari Punk Console by circuit benders for its distinctive low-fi sound similar to

classic Atari games.

3.)Pulse-width modulator:-

The 555 can be used to generate a variable Pulse-width modulation (PWM) signal using a few

external components. The chip alone can drive small external loads or an amplifying transistor

for larger loads.

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8.)555 IC DATASHEET

The LM555 is a highly stable device for generating accurate time delays or oscillation.

Additional terminals are provided for triggering or resetting if desired. In the time delay mode of

operation, the time is precisely controlled by one external resistor and capacitor. For astable

operation as an oscillator, the free running frequency and duty cycle are accurately controlled

with two external resistors and one capacitor. The circuit may be triggered and reset on falling

waveforms, and the output circuit can source or sink up to 200mA or drive TTL circuits.

555 Features:-

1. Direct replacement for SE555/NE555

2. Timing from microseconds through hours

3. Operates in both astable and monostable modes

4. Adjustable duty cycle

5. Output can source or sink 200 mA

6. Output and supply TTL compatible

7. Temperature stability better than 0.005% per °C

8. Normally on and normally off output

9. Available in 8-pin MSOP package

555 Applications:-

1. Precision timing

2. Pulse generation

3. Sequential timing

4. Time delay generation

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9.) IC CA3130

CA3130A and CA3130 are op amps that combine the advantage of both CMOS and bipolar

transistors. Gate-protected P-Channel MOSFET (PMOS) transistors are used in the input circuit

to provide very-high-input impedance, very-low-input current, and exceptional speed

performance. The use of PMOS transistors in the input stage results in common-mode input-

voltage capability down to 0.5V below the negative-supply terminal, an important attribute in

single-supply applications.

The CA3130 Series circuits operate at supply voltages ranging from 5V to 16V, (±2.5V to ±8V).

They can be phase compensated with a single external capacitor, and have terminals for

adjustment of offset voltage for applications requiring offset-null capability. Terminal provisions

are also made to permit strobing of the output stage. The CA3130A offers superior input

characteristics over those of the CA3130.

A Schematic Diagram Of CA3130 IC:-

Fig 8

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Figure 8

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10.)IC CA3130 Data Sheet:-

Introduction:-

CA3130A and CA3130 are op amps that combine the advantage of both CMOS and bipolar

transistors.

Gate-protected P-Channel MOSFET (PMOS) transistors are used in the input circuit to provide

very-high-input impedance, very-low-input current, and exceptional speed

performance. The use of PMOS transistors in the input stage results in common-mode input-

voltage capability down to 0.5V below the negative-supply terminal, an important

attribute in single-supply applications.

A CMOS transistor-pair, capable of swinging the output voltage to within 10mV of either

supply-voltage terminal (at very high values of load impedance), is employed as the output

circuit.

The CA3130 Series circuits operate at supply voltages ranging from 5V to 16V, (2.5V to 8V).

They can be phase compensated with a single external capacitor, and have terminals for

adjustment of offset voltage for applications requiring offset-null capability. Terminal provisions

are also made to permit strobing of the output stage.

The CA3130A offers superior input characteristics over those of the CA3130.

Features:-

MOSFET Input Stage Provides

Very High ZI = 1.5 TΩ (1.5 x 1012Ω) (Typ)

Very Low II . . . . . . . . . . . . . 5pA (Typ) at 15V Operation

Ideal for Single-Supply Applications

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Common-Mode Input-Voltage Range Includes Negative Supply Rail; Input Terminals

can be Swung 0.5V Below Negative Supply Rail

CMOS Output Stage Permits Signal Swing to Either (or both) Supply Rails

10.1)Applications:-

• Ground-Referenced Single Supply Amplifiers

• Fast Sample-Hold Amplifiers

• Long-Duration Timers/Monostables

• High-Input-Impedance Comparators (Ideal Interface with Digital CMOS)

• High-Input-Impedance Wideband Amplifiers

• Voltage Followers (e.g. Follower for Single-Supply D/A Converter)

• Voltage Regulators (Permits Control of Output Voltage Down to 0V)

• Peak Detectors

• Single-Supply Full-Wave Precision Rectifiers

• Photo-Diode Sensor Amplifiers

22

Absolute Maximum Ratings Thermal Information:-

DC Supply Voltage (Between V+ And V- Terminals) . . . . . . . . . .16V

Differential Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8V

DC Input Voltage . . . . . . . . . . . . . . . . . . . . . . (V+ +8V) to (V- -0.5V)

Input-Terminal Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1mA

Output Short-Circuit Duration (Note 1) . . . . . . . . . . . . . . . Indefinite

10.2)Thermal Information

Thermal Resistance (Typical, Note 2) θJA (oC/W) θJC (oC/W)

PDIP Package . . . . . . . . . . . . . . . . . . . 100 N/A

SOIC Package . . . . . . . . . . . . . . . . . . . 160 N/A

Metal Can Package . . . . . . . . . . . . . . . 170 85

Maximum Junction Temperature (Metal Can Package) . . . . . . .175oC

Maximum Junction Temperature (Plastic Package) . . . . . . . .150oC

Maximum Storage Temperature Range . . . . . . . . . . -65oC to 150oC

Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . .300oC

(SOIC - Lead Tips Only)

Operating Conditions:-

Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . -50C to 125C

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CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent

damage to the device. This is a stress only rating and operation of the

device at these or any other conditions above those indicated in the operational sections of this

specification is not implied.

NOTES:

1. Short circuit may be applied to ground or to either supply.

2. θJA is measured with the component mounted on an evaluation PC board in free air.

Electrical Specifications

TA = 25oC, V+ = 15V, V- = 0V, Unless Otherwise Specified

Typical Values Intended Only for Design Guidance, VSUPPLY = 7.5V, TA = 25oCUnless Otherwise Specified

The whole electrical specifications can be described in the following table:-

24

25

PARAMETER SYMBOL TEST

CONDITIONS

CA3130 CA3130A

UNITSMIN TYP MAX MI

N

TYPMAX

Input Offset Voltage|VIO| VS = ±7.5V - 8 15 - 2 5 mV

Input Offset Voltage

Temperature Drift

∆VIO/∆T - 10 - - 10 - µV/oC

Input Offset Current |IIO| VS = ±7.5V - 0.5 30 - 0.5 20 pA

Input Current II VS = ±7.5V - 5 50 - 5 30 p

Large-Signal

Voltage Gain

AOL VO = 10V

P 50 320 - 50 320 - kV/V

Common-Mode

Rejection Ratio

CMRR 94 110 - 94 110 - dB

Common-Mode

Input Voltage Range

VICR 70 90 - 80 90 -dB

d

Power Supply Rejection

Ratio

∆VIO/∆VS VS = ±7.5V 0 -0.5

to 12

10 0 -0.5 to

12

10 µV/V

Maximum Output

Voltage

VOM+ RL = 2kΩ 12 13.3 - 12 13 - V

VOM- RL = 2kΩ - 0.02 0.01 - 0.02 0.01 V

VOM+ RL = ∞ 14.99 15 - 14.

99

15 - V

VOM- RL = ∞ - 0 0.01 - 0 0.01 V

Maximum Output

Current

IOM+ (Source)

at VO = 0V

12 22 45 12 22 45 mA

IOM- (Sink) at

VO = 15V

12 20 45 12 20 45 mA

Supply Current I+ VO =

7.5V

- 10 15 - 10 15 mA

VO = 0V - 2 3 - 2 3 mA

11.)Typical Applications

Voltage Followers:-

Operational amplifiers with very high input resistances, like the CA3130, are particularly suited

to service as voltage followers. Figure 8 shows the circuit of a classical voltage follower,

together with pertinent waveforms using the CA3130 in a split-supply configuration. A voltage

follower, operated from a single supply, is shown in Figure 9, together with related waveforms.

This follower circuit is linear over a wide dynamic range, as illustrated by the reproduction of the

output waveform in Figure 9A with input-signal ramping. The waveforms in Figure 9B show

that the follower does not lose its input-to-output phase-sense, even though the input is being

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swung 7.5V below ground potential. This unique characteristic is an important attribute in both

operational amplifier and comparator applications. Figure 9B also shows the manner in which

the CMOS output stage permits the output signal to swing down to the negative supply-rail

potential (i.e., ground in the case shown). The digital-to-analog converter (DAC) circuit,

described later, illustrates the practical use of the CA3130 in a single-supply voltage-follower

application.

Fig 9

9-Bit CMOS DAC:-

A typical circuit of a 9-bit Digital-to-Analog Converter (DAC) is shown in Figure 10. This

system combines the concepts of multiple-switch CMOS lCs, a low-cost ladder network of

discrete metal-oxide-film resistors, a CA3130 op amp connected as a follower, and an

inexpensive monolithic regulator in a simple single power-supply arrangement. An

additional feature of the DAC is that it is readily interfaced with CMOS input logic, e.g., 10V

logic levels are used in the circuit of Figure 10. The circuit uses an R/2R voltage-ladder network,

with the output potential obtained directly by terminating the ladder arms at either the positive or

the negative power-supply terminal. Each CD4007A contains three “inverters”, each “inverter”

functioning as a single-pole double-throw switch to terminate an arm of the R/2R network at

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either the positive or negative power-supply terminal. The resistor ladder is an assembly of 1%

tolerance metal-oxide film resistors. The five arms requiring the highest accuracy are assembled

with series and parallel combinations of 806,000Ω resistors from the same manufacturing lot. A

single 15V supply provides a positive bus for the CA3130 follower amplifier and feeds the

CA3085 voltage regulator. A “scale-adjust” function is provided by the regulator output

control, set to a nominal 10V level in this system. The linevoltageregulation (approximately

0.2%) permits a 9-bit accuracy to be maintained with variations of several volts in the supply.

The flexibility afforded by the CMOS building blocks simplifies the design of DAC systems

tailored toparticular needs.

Single-Supply, Absolute-Value, Ideal Full-Wave Rectifier:-

The absolute-value circuit using the CA3130 is shown in Figure 11. During positive excursions,

the input signal is fed through the feedback network directly to the output. Simultaneously, the

positive excursion of the input signal also drives the output terminal (No. 6) of the inverting

amplifier in a negative-going excursion such that the 1N914 diode effectively disconnects the

amplifier from the signal path. During a negative-going excursion of the input signal, the

CA3130 functions as a normal inverting amplifier with a gain equal to -R2/R1. When the

equality of the two equations shown in Figure 11 is satisfied, the full-wave output is

symmetrical.

Peak Detectors:-

Peak-detector circuits are easily implemented with the CA3130, as illustrated in Figure 12 for

both the peak-positive and the peak-negative circuit. It should be noted that with large-signal

inputs, the bandwidth of the peak-negative circuit is much less than that of the peak-positive

circuit. The second stage of the CA3130 limits the bandwidth in this case. Negative-going

output-signal excursion requires a positive-going signal excursion at the collector of transistor

Q11, which is loaded by the intrinsic capacitance of the associated circuitry in this mode. On the

other hand, during a negative-going signal excursion at the collector of Q11, the transistor

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functions in an active “pull-down” mode so that the intrinsic capacitance can be discharged more

expeditiously.

Error-Amplifier in Regulated-Power Supplies:-

The CA3130 is an ideal choice for error-amplifier service in regulated power supplies since it

can function as an erroramplifierwhen the regulated output voltage is required to approach zero.

Figure 13 shows the schematic diagram of a 40mA power supply capable of providing regulated

output voltage by continuous adjustment over the range from 0V to 13V. Q3 and Q4 in lC2 (a

CA3086 transistor-array lC) function as zeners to provide supply-voltage for the CA3130

comparator (IC1). Q1, Q2, and Q5 in IC2 are configured as a low impedance, temperature-

compensated source of adjustable reference voltage for the error amplifier. Transistors Q1, Q2,

Q3, and Q4 in lC3 (another CA3086transistor-array lC) are connected in parallel as the

seriespasselement. Transistor Q5 in lC3 functions as a currentlimitingdevice by diverting base

drive from the series-pass transistors, in accordance with the adjustment of resistor R2. Figure 14

contains the schematic diagram of a regulated power-supply capable of providing regulated

output voltage by continuous adjustment over the range from 0.1V to 50V and currents up to 1A.

The error amplifier (lC1) and circuitry associated with lC2 function as previously described,

although the output of lC1 is boosted by a discrete transistor (Q4) to provide adequate base drive

for the Darlington Darlingtonconnectedseries-pass transistors Q1, Q2. Transistor Q3 functions in

the previously described current-limiting circuit.

Multivibrators:-

The exceptionally high input resistance presented by the CA3130 is an attractive feature for

multivibrator circuit design because it permits the use of timing circuits with high R/C ratios.

The circuit diagram of a pulse generator (astablemultivibrator), with provisions for independent

control of the “on” and “off” periods, is shown in Figure 15. Resistors R1 and R2 are used to

bias the CA3130 to the mid-point of the supply-voltage and R3 is the feedback resistor. The

pulse repetition rate is selected by positioning S1 to the desired position and the rate remains

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essentially constant when the resistors which determine “on-period” and “off-period” are

adjusted.

Function Generator:-

Figure 16 contains a schematic diagram of a function generator using the CA3130 in the

integrator and threshold detector functions. This circuit generates a triangular or square-wave

output that can be swept over a 1,000,000:1 range (0.1Hz to 100kHz) by means of a single

control, R1. A voltage-control input is also available for remote sweepcontrol. The heart of the

frequency-determining system is an operational-transconductance-amplifier (OTA) (see Note

10), lC1, operated as a voltage-controlled current-source. The output, IO, is a current applied

directly to the integrating capacitor, C1, in the feedback loop of the integrator lC2, using

a CA3130, to provide the triangular-wave output. Potentiometer R2 is used to adjust the circuit

for slope symmetry of positive-going and negative-going signal excursions. Another CA3130,

IC3, is used as a controlled switch to set the excursion limits of the triangular output from the

integrator circuit. Capacitor C2 is a “peaking adjustment” to optimize the high-frequency square-

wave performance of the circuit. Potentiometer R3 is adjustable to perfect the “amplitude

symmetry” of the square-wave output signals. Output from the threshold detector is fed back via

resistor R4 to the input of lC1 so as to toggle the current source from plus to minus

in generating the linear triangular wave.

12.)Application Information:-

Circuit Description:-

Figure 1 is a block diagram of the CA3130 Series CMOS Operational Amplifiers. The input

terminals may be operated down to 0.5V below the negative supply rail, and the output

30

can be swung very close to either supply rail in many applications. Consequently, the CA3130

Series circuits are ideal for single-supply operation. Three Class A amplifier stages, having the

individual gain capability and current consumption shown in Figure 1, provide the total gain of

the CA3130. A biasing circuit provides two potentials for common use in the first and second

stages. Terminal 8 can be used both for phase compensation and to strobe the output stage into

quiescence. When Terminal 8 is tied to the negative supply rail (Terminal 4) by mechanical or

electrical means, the output potential at Terminal 6 essentially rises to the positive supply-rail

potential at Terminal 7. This condition of essentially zero current drain in the output stage under

the strobed “OFF” condition can only be achieved when the ohmic load resistance presented to

the amplifier is very high (e.g.,when the amplifier output is used to drive CMOS digitalcircuits in

Comparator applications).

Input Stage:-

The circuit of the CA3130 is shown in the schematic diagram. It consists of a differential-input

stage using PMOS field-effect transistors (Q6, Q7) working into a mirror-pair of bipolar

transistors (Q9, Q10) functioning as load resistors together with resistors R3 through R6. The

mirror-pair transistors also function as a differential-to-single-ended converter to provide

base drive to the second-stage bipolar transistor (Q11). Offset nulling, when desired, can be

effected by connecting a 100,000Ω potentiometer across Terminals 1 and 5 and the

potentiometer slider arm to Terminal 4. Cascade-connected PMOS transistors Q2, Q4 are the

constant-current source for the input stage. The biasing circuit for the constant-current source is

subsequently described. The small diodes D5 through D8 provide gate-oxide protection against

high-voltage transients, including static electricity during handling for Q6 and Q7.

13.)APPLICATIONS OF GSM DETECTOR:-

1. School / Universities

During tests and exams the use of mobile phones is prohibited, for the students could use it to

send answers among each other.

31

By using a gsm-detector this kind of fraud is prohibited. The presence of a gsm-detector can

work in a preventing way, because when a gsm-detector is present, the use of mobile phones

does not stay unnoticed.

2. Cinemas

In a cinema the use of a mobile phone is undesired. Being called by someone during a movie is

of course very bothering for other people.

With a gsm-detector the use of mobile phones is detected, so the visitor can be informed that this

is not allowed.

3. Theatres

Just like with a cinema, in theatres the use of mobile phones is not allowed. The gsm-detector

can be used to prevent use.

4. Restaurants / Hotels

In hotels and restaurants it is often undesired that a mobile phone is used at the table or in other

areas. A gsm-detector can be installed in these areas to notify guests.

5. Petrol stations

When tanking at a petrol station, the use of mobile phones is prohibited, because the mobile

signals can interfere with the tanking equipment and because a small spark within the mobile

phone could set fire to possible gasoline vapour.

With the gsm-detector this prohibition is pointed out to the tanking customer.

6. Airplanes

32

In airplanes the use of mobile phones is prohibited, for it could interfere with the equipment in

the airplane. All the while phones are still used illegally, especially in restrooms. By installing a

gsm-detector there, this can be prevented.

7. Conference rooms

It is often distracting to be called during a meeting. Also, confidential conversation could be

overheard by using cell phones, especially by those with a spy function (when someone calls that

phone it automatically is picked up without ringing, so that the person on the other end of the

line can hear conversations in the room where the spy phone is placed).

By using a gsm-detector you can be assured that this is not the case.

8. Hospitals

The signals emitted by mobile phones can interfere with some electronic equipment inside the

hospital. This could have fatal consequences.

The gsm-detector can be placed in any area where the use of mobile phones could interfere with

sensitive devices. The audio alarm will sound when a phone is used and this way, the person

should immediately switch off his/her phone.

9. Prisons

In prisons the use of mobile phones is not allowed. It could occur anyway. By using the gsm-

detector the staff can be notified when a mobile phone is used inside the facility.

10. Power plants

33

Power plants contain -just like hospitals- a lot of electronic devices that are sensitive for

interference by mobile phones. Therefore, it is prohibited to use mobile phones there. Use a gsm-

detector to inspect this.

11. Petrochemical industry

Just like in power plants, the petrochemical industry makes use of sensitive equipments. In this

branch of industry the materials that are being processed are often highly flammable or

explosive. Tiny sparks that can occur within a gsm telephone could lead to explosions. With the

gsm-detector the unauthorized use of mobile phones can be traced.

12. Etcetera

Evidently these are not the only applications of the gsm-detectr. Maybe you can come up with

one for your own situation. The gsm-detector can be placed anywhere and has various ways of

notifying. Because of this, the device is suitable for more applications, such as:

Customs

Stores

Court rooms

CONCLUSION:-

During tests and exams the use of mobile phones is prohibited, for the students could use

it to send answers among each other.

34

By using a gsm-detector this kind of fraud is prohibited. The presence of a gsm-detector

can work in a preventing way, because when a gsm-detector is present, the use of mobile

phones does not stay unnoticed.

In a cinema the use of a mobile phone is undesired. Being called by someone during a

movie is of course very bothering for other people.

With a gsm-detector the use of mobile phones is detected, so the visitor can be informed

that this is not allowed.

REFERENCES

1. http://www.datasheetcatalog.org/datasheet/SGSThomsonMicroelectronics/mXvzqv. pdf

35

2. http://www.google.co.in/#hl=en&sugexp=les%3B&gs_nf=3&pq=rf%20transmitter

%20receiver%20module&cp=6&gs_id=5x&xhr=t&q=ne555+datasheet&pf=p&

tbo=d&sclient=psy-ab&oq=ne555+&gs_l=&pbx=1&bav=on.2,or.r_gc.r_pw.r_

qf.&fp=6cb6d6cd7d527d06&bpcl=38897761&biw=800&bih=451

3. Basic electronics by J.B Gupta.

4. http://www.sensorsmag.com/sensors/acoustic-ultrasound/choosing-ultrasonic-sensor-

proximity-or-distance-measurement-825

5. www.electricalprojects.com

6. www.ti.com/lit/ds/symlink/lm555.pdf

APPENDIX A

NE555 DATASHEET

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37

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APPENDIX B

HT 12E DATASHEET

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40

41

APPENDIX C

HT 12D DATASHEET

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43

44

45