Cell Phone Controlled Relay

            Now a days all of them are using various types of cell phone in the world. Imagine that from your cell phone you can control a relay which is connected to you home gate lights or other equipment's in the house. So i build a circuit for this application.While calling to someone, if we press any button in the cell phone a tone produced and the receiver can heard.This tone is called DTMF (Dual Tone Multi Frequency).For more about DTMF, see my previous post.The working of the circuit is based on this principle. 

                                                 Click the circuit for enlarging.

DTMF Decoder

      While calling to someone, if we press any button in the cell phone a tone produced and the receiver can heard.This tone is called DTMF (Dual Tone Multi Frequency). DTMF assigns a specific frequency (consisting of two separate tones) to each key so that it can easily be identified by the electronic circuit. The signal generated by the DTMF encoder is a direct algebraic summation, in real time, of the amplitudes of two sine (cosine) waves of different frequencies, i.e., pressing ‘5’ will send a tone made by adding 1336 Hz and 770 Hz to the other end of the line. The tones and assignments in a DTMF system are shown below.

  

Frequencies	1209 Hz	1336 Hz	1477 Hz	1633 Hz
697 Hz	1	2	3	A
770 Hz	4	5	6	B
852 Hz	7	8	9	C
941 Hz	*	0	#	D

      An MT8870 series DTMF decoder is used here. All types of the MT8870 series use digital counting techniques to detect and decode all the 16 DTMF tone pairs into a 4-bit code output. The built-in dial tone rejection circuit eliminates the need for pre-filtering. When the input signal given at pin 2 (IN-) in single-ended input configuration is recognised to be effective, the correct 4-bit decode signal of the DTMF tone is transferred to Q1 (pin 11) through Q4 (pin 14) outputs.The circuit is shown below.

3.5mm Headphone Jack

         3.5 mm Headphone Jack is a 1/8 inch or 3.5 mm headphone jack is an audio socket that accepts a 3.55 mm male pin or audio plug. A small round connector for accepting the pin-shaped plug from a standard pair of music headphone. Below schematic shows the typical diagram of 3.5mm Headphone Jack.

3.5mm Headphone Jack Schematic Diagram 

• 1 – tip : audio out left channel. 
• 2 – 1° ring : audio out right channel. 
• 3 – 2° ring : microphone line in. 
• 4 – 3° ring/sleeve : ground – common for microphone and audio out.

       In circuits we only need the Speaker +ve and the speaker ground. For circuit, Tip pin as the 1 and the ring pin as either the right channel out (pin 2) or left channel out (pin 1). The modified schematic diagram of the 3.5 mm Headphone Jack for circuits is below (for electronics application).

Standard 5v Regulated Power Supply

             For the proper working of every muc based projects a regulated 5v power supply is required. The standard voltage for all the muc( Atmel,AVR,Pic ) are 5v. So i prepared the circuit for the power supply.The circuit for the power supply is below.

Click the circuit for enlarging

4 Channel Led Chaser

                 This LED chaser display is build around readily available, low cost components.This circuit is easy for build for a beginner in the electronics. The power supply for the chaser circuit is from a 9v battery.The circuit diagram of the chaser is below.

                                                       Click the circuit for enlarging.

                The NE 555 timer ic and decade counter 4017 is the heart of the circuit. The astable multivibrator built around IC2 produces a clock frequency at its output pin 3. This output is connected to clock pin (pin 14) of the decade counter Cd 4017.The decade counter can count up to 10. But in circuit we only use 4 O\P so the Q4 (pin 10)  is connected to the reset (pin 15) of the CD 4017. The output of IC3 advances by one count every second (depending on the time period of astable multivibrator IC2). The VR1 connected between the Pins of IC2 determine the speed of the glowing of the bulb.

Arduino UNO - R3

               This is the new Arduino Uno R3. In addition to all the features of the previous board, the Uno now uses an ATmega16U2 instead of the 8U2 found on the Uno (or the FTDI found on previous generations). This allows for faster transfer rates and more memory. No drivers needed for Linux or Mac (inf file for Windows is needed and included in the Arduino IDE), and the ability to have the Uno show up as a keyboard, mouse, joystick, etc.
     
                           

     

Arduino Duemilanove

                   This is the latest revision of the basic Arduino USB board. It connects to the computer with a standard USB cable and contains everything else you need to program and use the board. It can be extended with a variety of shields. Arduino is an open-source physical computing platform based on a simple i/o board and a development environment that implements the Processing / Wiring language. Arduino can be used to develop stand-alone interactive objects or can be connected to software on your computer (e.g. Flash, Processing, MaxMSP). The open-source IDE can be downloaded for free (currently for Mac OS X, Windows, and Linux).
                                  

What is a Raspberry Pi

The Raspberry Pi is a credit-card sized computer that plugs into your TV and a keyboard. It’s a capable little PC which can be used for many of the things that your desktop PC does, like spreadsheets, word-processing and games. It also plays high-definition video. 


The Raspberry Pi measures 85.60mm x 56mm x 21mm, with a little overlap for the SD card and connectors which project over the edges. It weighs 45g. 

The SoC is a Broadcom BCM2835. This contains an ARM1176JZFS, with floating point, running at 700Mhz, and a Videocore 4 GPU. The GPU is capable of BluRay quality playback, using H.264 at 40MBits/s. It has a fast 3D core accessed using the supplied OpenGL ES2.0 and OpenVG libraries.

                                

16 Led Chaser

            The heart of the project is Microchip Pic 16F628A. The Pic 16F628A muc can show various type of led design. You can seen in the above video.The 8 O\P of muc drives the 16 leds. The push button help to change the led pattern.

Digital Security System

Inside the security system.....

                         

Cell phone controlled car without micro controller

I had made this cell phone controlled car for my project. In every cell phone controlled car there is costly micro controller. But in my car i don't use a  micro controller. so the programming is not need for my car.  So every beginners in the electronics can do this project.

The car can move forward, backward, Left turn, Right turn, Rotating clock wise, Anti rotating clock wise.

The main part of the car is DTMF decoder ic and a motor driver. The DTMF decoder decodes the signals from the mobile and send to the motor driver ic. For every decoded signal there is a movement in the car.

My Old Prototype 

New Prototype 

     The post will updated with circuits. So keep visiting or follow the blog. 

Cell Phone controlled home appliances

Prototype of the cell phone controlled home 

appliances

Rectifier

A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. The process is known as rectification.









Half wave rectification

4000 Series IC

                       There are many ICs in the 4000 series and this page only covers a selection, concentrating on the most useful ICs. Most gates and a few counters are covered. For each IC there is a diagram showing the pin arrangement and brief notes explain the function of the pins where necessary.

555 Timer Ic

One commonly used circuit is the 555 IC which is a highly stable controller capable of producing timing pulses. With a monostable operation, the T(time) delay is controlled by one external resistor and one capacitor. With an astable operation, the frequency and duty cycle are accurately controlled by two external resistors and one capacitor.The application of this integrated circuit is in the areas of PRECISION TIMING, PULSE GENERATION, TIMING DELAY GENERATION and SEQUENTIAL TIMING.
                                     
 

Clock Controller

                    The Clock Controller V1.1was designed to be an exemplary of using 'C' language to control timer0interrupt, 7-segment LED and keypad scanning. It provides 1-bit sink currentdriving output, for driving a relay, opto-triac, say. Many projects requiring7-segment display and keypad interfacing may get the idea from the Clockcircuit and software.
 

                       

                        Circuit diagram of the Clock Controller  P10-P1.7 drives 7-segment commonanode LED with sink current. P3.0-P3.3 also drives a base pin of 4-PNPtransistor, 2n2907 with sink current. As shown in the figure, the 2nd 2-digitLED that connected to P3.2 and P3.3 is rotated 180 degrees to the 1st 2-digitallowing the pt. segment to be used for 1 second blinking. P3.0-P3.3 alsoconnects four momentary switches while the other legs are tied to inputport P3.4. During display and key switch scanning, a logic '0' is shiftedfrom P3.0 to P3.3,  if there was a key pressed, P3.4 then became low.P3.7 is a 1-bit sink current driving, an example in the circuit uses a2n2907 to drive a small electromechanical relay 5V.

For more:.....................

Multiplexing

Multiplexing is a very efficient technique for controlling many components wired together in a matrix/array.  In this example, I'll be talking exclusively about multiplexing an array of LEDs, but the same basic principles apply to other multiplexed components (sensors, buttons, etc).

   
In a multiplexed array of LEDs, only one row of LEDs is on at any given time.  It seems like this would limit the types of shapes we can display on the LED matrix, but it actually doesn't.  This is because the arduino (or whatever is sending data to the array) is switching through each row so quickly (hundreds or thousands of times a second) that we do not perceive the flashing on and off of each consecutive row.  You can read more about this phenomenon, called persistence of vision, on wikipedia.            
                                  

So how do we send data to one row at a time?  If we connect five volts (red) to one row and connect ground (blue) to the other three rows and cycle through each row one by one, it will look something like figure 1.  Now image that while one of the rows is at +5, we connect one of the columns to ground.  As shown in figure 2, this will cause the LED at the junction of the +5 row and GND column to light up.  This way, we can address each of the 16 LEDs in the matrix individually using only eight leads (four to the rows and four to the columns).



Now look at the image below.  Imagine if we very quickly turn on the LED in the upper left corner (position 1,1), then the LED at (2,2), then (3,3) and (4,4), and we cycle between these four LEDs very quickly (hundreds of times a second).  It will appear that all four of these LEDs are on a the same time (as shown in right image in the image below).  Study the diagram below and convince yourself that this is true.
                    

Soldering Techniques

1.     Study the diagram and PCB layout.

2.     Check all the components and study their pins and orientation.

3.   Clean the leads of components if needed to remove rust or grease with a blade.

4.     Place resistors first then IC base, capacitors etc.

5.     Use little flux to the joints to increase the melting point of solder lead.

Perf board Circuit Construction

Printed circuit board, or PCB, is used to mechanically support the electronic components and to connect them electrically using conductive pathways called tracks etched from copper sheets. Besides etched PCBs, there are Common or General purpose PCBs to make temporary or permanent circuits boards. Here explains the types of General purpose PCBs.

Perf Board

Most experimenters are familiar with "Perf board" which is a pre-drilled circuit for creating prototypes of simple circuits. It's not too expensive and for more easier to get started with than etching PCB's.

                               

 The components are mounted by inserting the leads through the most appropriate holes then are wired on the back side, usually by bending the leads over to the desired connection point.

Transistors

Transistors may be in plastic or metal can packages. Value of the transistor is printed on its body. Pin numbers are generally assigned as 1,2 and 3 from the facing side.
  

General purpose NPN transistors have pins 1-Collector, 2-Base, 3- Emitter. That is CBE. In PNP types the pins are reversed. 1-Emitter, 2-Base and 3- Collector. That is EBC. Metal can transistors have a small projection in the rim of the body.

The pin close to it is the emitter. Pin opposite to the emitter is Collector and the middle pin is base. Pin assignment of some common transistors is given below.

 

    

Transistor	Type	Pins 1 2 3	Transistor	Type	Pins 1 2 3
BC546,547,548,549 550, BC 337,AC 187	NPN	CBE	2N 2222A,2N 3904	PNP	EBC
TIP 120,121,122	NPN	BCE	TIP 125,126,127	PNP	EBC
BD139	NPN	ECB	BD140	PNP	ECB
BF494,495	NPN	CEB	MPSA 92,42,44	PNP	EBC
C2570	NPN	BEC	BC636	PNP	BCE
C1730	NPN	ECB	SK/CK/BEL100P	PNP	EBC
BD677	NPN	BCE	AC188	PNP	EBC
D882 / 2SD882	NPN	ECB	BC557	PNP	EBC
D313/MJE 13005	NPN	BCE	BC558	PNP	EBC

5 Band Resistor Color Codes

This calculator converts resistor values to or from 5-band or 4-band colour codes.

To convert from value to colours:

Select the resistor type (4 or 5 bands) using the radio buttons. Type the resistance in the box below and select the units and (optionally) the tolerance from the drop-down boxes. The colour bands will be displayed below on the image of the resistor.

To convert from colours to value:

Select the resistor type (4 or 5 bands) using the radio buttons. Hover the mouse over the coloured bands on the image of the resistor to display the colour selector box, then click on the required colour. Repeat for all bands (tolerance is optional). The resistance will be shown in the box above the image, along with the units and tolerance.

Download  Electronics Assistant

source

Seven Segment Display

A seven-segment display (SSD), or seven-segment indicator, is a form of electronic display device for displaying decimal numerals that is an alternative to the more complex dot-matrix displays. Seven-segment displays are widely used in digital clocks, electronic meters, and other electronic devices for displaying numerical information.

The segments of a 7-segment display are referred to by the letters A to G, as follows:

       
 

where the optional DP decimal point (an "eighth segment") is used for the display of non-integer numbers.

Resistor Color Code

v

The color codes of a resistor are read from left to right, with the tolerance band oriented to the right side. Match the color of the first band to its associated number under the digit column in the color chart. This is the first digit of the resistance value. Match the second band to its associated color under the digit column in the color chart to get the second digit of the resistance value.

Match the color band preceding the tolerance band (last band) to its associated number under the multiplier column on the chart. This number is the multiplier for the quantity previously indicated by the first two digits (four band resistor) or the first three digits (five band resistor) and is used to determine the total marked value of the resistor in ohms.

To determine the resistor's tolerance or possible variation in resistance from that indicated by the color bands, match the color of the last band to its associated number under the tolerance column. Multiply the total resistance value by this percentage.

For example, the first resistor shown at the top of this page has a resistance of (47 X 100) = 4700 ohms. The tolerance is plus or minus (10% X 4700) = plus or minus 470 ohms. The second resistor has a resistance of (470 X 1) = 470 ohms. The tolerance is plus or minus (2% X 470) = plus or minus 9.4 ohms.

You can download resistor color code software from here.

Resistor color code

Resistor color code 2

Capacitor Conversion

Microfarads (uF)                       Nanofarad (nF)                    Picofarads (pF)

      0.000001                                           0.001                                                 1

      0.00001                                             0.01                                                   10

      0.0001                                               0.1                                                     100

      0.001                                                 1                                                        1000

      0.01                                                   10                                                      10000

       0.1                                                    100                                                    100000

   
       1                                                       1000                                                  1000000

      10                                                      10000                                                10000000

      100                                                    100000                                              100000000

Light Switch

The circuit which is being presented here is a switch that will be activated by light falling on a sensor.The circuit uses a Light Dependent Resistor (LDR) as a sensor and three transistors to amplify the signals from the LDR and drive the relay which does the switching.

Led Chaser

Automatic room light with visitor counter

When somebody enters into the room the counter incremented by one and the light in the room will be switched ON and when any one leaves from the room  the counter is decremented by one. The light will be only switched OFF until all the persons in the room go out.The total number of persons inside the room is also displayed on the seven segment displays.