Cell Phone Signal Jammer using IC555

The 555 timer [8 pin] IC simply makes a noise. It’s coupled via C4 [electrolytic] to modulate the MRF transistor oscillator. With C1 set at roughly 1/3rd, you will be close to 900 MHz. By sweeping the C1 trimmer capacitor, you can swing the output frequency from 800 MHz to 2 GHz with the transistor and values shown. You could replace the 555 chip with an electret microphone and listen to yourself talk on a scanner, so the unit could easily couple as a UHF Bug. Instead of a single Tapped Coil, I’ve used two molded inductors for ease of construction.Values for C1,C2,L1,L2 are critical for the frequency range. You might want to build the unit...

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Pulse Width Modulation DC Motor Control

Parts List - R1 - 1 Meg 1/4W Resistor R2 - 100K Pot C1 - 0.1uF 25V Ceramic Disc Capacitor C2 - 0.01uF 25V Ceramic Disc Capacitor Q1 - IRF511 MOSFET U1 - 4011 CMOS NAND Gate S1 - DPDT Switch M1 - Motor (See Notes) MISC - Case, Board, Heatsink, Knob For R2, Socket For U1 Notes 1. R2 adjusts the speed of the oscillator and therefore the speed of M1. 2. M1 can be any DC motor that operates from 6V and does not draw more than the maximum current of Q1. The voltage can be increased by connecting the higher voltage to the switch instead of the 6V that powers the oscillator. Be sure not to exceed the power rating of Q1 if you do this. 3....

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FM Transmitter

Parts List - C1 - 0.001uf Disc Capacitor C2 - 5.6pf Disc Capacitor C3,C4 - 10uf Electrolytic Capacitor C5 - 3-18pf Adjustable Cap R1 - 270 Ohm 1/8W Resistor R2,R5,R6 - 4.7k 1/8W Resistor R3 - 10k 1/8W Resistor R4 - 100k 1/8W Resistor Q1, Q2 - 2N2222A NPN Transistor L1, L2 - 5 Turn Air Core Coil MIC - Electret Microphone MISC - 9V Battery Snap, PC Board, Wire For Antenna Notes 1. L1 and L2 are 5 turns of 28 AWG enamel coated magnet wire wound with a inside diameter of about 4mm. The inside of a ballpoint pen works well (the plastic tube that holds the ink). Remove the form after winding then install the coil on the circuit board,...

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Stepper Motor Controller

Parts - R1, R2 ,R3, R4 - 1K 1/4W Resistor D1, D2, D3, D4 - 1N4002 Silicon Diode Q1, Q2, Q3, Q4 - TIP31 NPN Transistor (See Notes) TIP41, 2N3055 U1 - 4070 CMOS XOR Integrated Circuit U2 - 4027 CMOS Flip-Flop S1 - SPDT Switch MISC - 1 Case, Board, Wire, Stepper Motor Notes 1. You should be able to substitute any standard (2N3055, etc.) power transistor for Q1-Q4. 2. Every time the STEP line is pulsed, the motor moves one step. 3. S1 changes the motors directi...

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Solar Charger for 6V Battery

The circuit uses a 12 volt solar panel and a variable voltage regulator IC LM 317. The solar panel consists of solar cells each rated at 1.2 volts. 12 volt DC is available from the panel to charge the battery. Charging current passes through D1 to the voltage regulator IC LM 317. By adjusting its Adjust pin, output voltage and current can be regulated. VR is placed between the adjust pin and ground to provide an output voltage of 9 volts to the battery. Resistor R3 Restrict the charging current and diode D2 prevents discharge of current from the battery. Transistor T1 and Zener diode ZD act as a cut off switch when the battery is full. Normally...

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RFID Based Attendance System (AT89S52 + RFID)

The attendance system is basically an embedded one. Embedded stands for ‘hardware controlled by software’. Here, the software using a Microcontroller controls all the hardware components. The microcontroller plays an important role in the system. The main objective of the system is to uniquely identify and to make attendance for a person. This requires a unique product, which has the capability of distinguishing different person. This is possible by the new emerging technology RFID (Radio Frequency Identification). The main parts of an RFID system are RFID tag (with unique ID number) and RFID reader (for reading the RFID tag). In this system,...

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InfraRed Remote Switch (AT89S52) Electronic Project

This Project “REMOTE CONTROLLED SWITCH BOARD” is used to switch on/off the Home Appliances by using a standard Remote control. The system is used to switch on/off upto six electrical devices. All the above processes are controlled by the 8 bit Microcontroller AT89C52. The Microcontroller receives the Infrared Signal from the receiver and it decodes and switch on/off the appropriate Device. The Range of the system is unto 10 meters. The project can switch on/off electrical devices of maximum load current of 5Amperes. High power loads can also be connected by changing the Relay. The conditions of the devices are stored in the EEPROM IC. And the...

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Electronic Voting Machine (AT89S8252) Electronic Projects

Now-a-days Electronic voting machines are being used effectively. The confidence of the voter in its flawless working is gradually building up and these machines are thus becoming quite popular throughout the country. Features of the electronic voting machine include avoidance of invalid votes and reduction of counting time and the consequent expenditure incurred on manpower deployment. By using the Microcontroller the voting machine can be built up easily and it will make simple to operate. Download Full Project Rep...

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Electronic Projects : Auto Control of three phase Induction motor (AT89C51)

This Project can be used with the three phase Induction motors. The circuit will take the full control of the motor and it will protect the motor from several faults such us over voltage and under voltage and the circuit will switch on the motor under safety conditions. The circuit was fully controlled by the microcontroller and the microcontroller will continuously monitors the voltages of the three phase and if the voltage goes abnormal then it will switch off the motor until they are normal. All the conditions are displayed it over the LCD display. In our project we are using the popular 8 bit microcontroller AT89S52. It is a 40 pin microcontroller. Download...

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GSM Controlled Robot - Electronic Project

In the project the robot is controlled by a mobile phone that makes a call to the mobile phone attached to the robot. In the course of a call, if any button is pressed a tone corresponding to the button pressed is heard at the other end called ‘Dual Tone Multiple frequency’ (DTMF) tone. The robot receives these tones with help of phone stacked in the robot. The received tone is processed by the microcontroller with the help of DTMF decoder ic cm8870 . This ic sends a signals to the the motor driver ic l293d which derives the motor forward, reverse…etc. Project is built using AVR microcontroller the ATmega16. Project is a very simple and a...

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Automatic Room Light Controller with Visitor Counter - Electronic Project

There are two diffrent hex.files in project - 1) ir.hex : it is for proteus simulation it will not work proper in 16*1 lcd if u use 16*2 or more then it is ok 2) 2051.hex : this is a real hex file that u has to burn in 2051 microcontroller with lcd 16*1 if u want to use other then it also work. Download Full Project Rep...

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Scrolling LED Message Display - 8051 Electronic Projects

This project is a scrolling dot matrix LED message display powered by 8051 microcontroller. The code is written in assembly to control four 8x8 dot matrix LED display segments. Message to be displayed is stored in I2C EEPROM memory which is configurable through uart. Author has provided a VB software for easy configuration of message display from your PC. User can not only set type of meesage to be displayed on LED display, but also control scrolling speed of message. There are two gui software provided in the package one is a simple interface and second software provides advance features to user with preview of message before saving settings...

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Magnetic proximity sensors

Here is an interesting circuit for a magnetic proximity switch which can be used in various applications. The magnetic proximity switch circuit, in principle, consists of a reed switch at its heart. When a magnet is brought in the vicinity of the sensor (reed switch), it operates and controls the rest of the switching circuit. In place of the reed switch, one may, as well, use a general-purpose electromagnetic reed relay (by making use of the reed switch contacts) as the sensor, if required. These tiny reed relays are easily available as they are widely used in telecom products. The reed switch or relay to be used with this circuit should be...

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Power supply failure alarm

Most of the power supply failure indicator circuits need a separate power supply for themselves. But the alarm circuit presented here needs no additional supply source. It employs an electrolytic capacitor to store adequate charge, to feed power to the alarm circuit which sounds an alarm for a reasonable duration when the supply fails. This circuit can be used as an alarm for power supplies in the range of 5V to 15V. To calibrate the circuit, first connect the power supply (5 to 15V) then vary the potentiometer VR1 until the buzzer goes from on to off. Whenever the supply fails, resistor R2 pulls the base of transistor low and saturates it,...

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6 WATT POWER AMPLIFIER

The TA7222 is a power amplifier for consumer application. It is designed for high power, low distortion and low noise. It also contains various kind of protectors. It is suitable for car – audio power amplifier with high performance. Operating Supply Voltage Range Vcc = 9~18volt High power is 6Watt COMPONENTS LIST Resistors: P1=100kΩ R1=27 kΩ R2=220Ω Capacitors: C1=4,7μF/50V C2=470μF/22V C3=47μF/22V C4=100nF C5=47μF/22V C5=470μF/22V Semiconductors: IC1= TA7222AP Miscellaneous: Heatsink for ...

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