Category: Circuti Ideas


BLOCK DIAGRAM OF
SOLAR TRACKING SYSTEM


SCHEMATIC DIAGRAM OF
SOLAR TRACKING SYSTEM

READ TIME FROM RTC (REAL TIME CLOCK)AND CALCULATE REQUIRED ANGLE OF INCLINATION

MEASURE PRESENT INCLINATION ANGLE THROUGH POSION OF 10K/OHM VARIABLE RESISTOR

IF POSITION SOLAR PANNEL IS NOT CORRECT ROTATE THE STEPPER MOTOR TO CORRECT THE POSITION

PANNEL VOLTAGE AND PANNEL CURRENT IS ALSO DISPLAYED ON LCD

THIS PROJECT IS AVAILABLE  IN BOTH SINGLE & dOUBLE ROTATION.


		
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RFiD Based Door Access Control

RFiD Based Door Access Control

SYNOPSIS

The concept of access control is brought about using a card, a corresponding card reader and a control panel interfaced with the server. The card is a proximity card with a unique identification number integrated in it. The reader reads the data and sends it to the control panel, which is the micro controller. This controller checks the validity of the data with the server, which bears the database. The server is loaded with the details about the employee for that number.

The control panel checks whether he/she is allowed to enter the particular door or not. If the employee is authentic, then he/she is allowed access in the particular entrance.

The employees can be permitted in a given entrance as per his/her designation. The access control is employed at this point. When a person of a particular designation is not supposed to be allowed in a given entrance.

CIRUIT DIAGRAM

rfid based access system ckt

Radio frequency (RF) refers to electromagnetic waves that have a wavelength suited for use in radio communication. Radio waves are classified by their frequencies, which are expressed in kilohertz, megahertz, or gigahertz. Radio frequencies range from very low frequency (VLF), which has a range of 10 to 30 kHz, to extremely high frequency (EHF), which has a range of 30 to 300 GHz.

RFID is a flexible technology that is convenient, easy to use, and well suited for automatic operation. It combines advantages not available with other identification technologies. RFID can be supplied as read-only or read / write, does not require contact or line-of-sight to operate, can function under a variety of environmental conditions, and provides a high level of data integrity. In addition, because the technology is difficult to counterfeit, RFID provides a high level of security.

RFID is similar in concept to bar coding. Bar code systems use a reader and coded labels that are attached to an item, whereas RFID uses a reader and special RFID devices that are attached to an item. Bar code uses optical signals to transfer information from the label to the reader; RFID uses RF signals to transfer information from the RFID device to the reader.

Radio waves transfer data between an item to which an RFID device is attached and an RFID reader. The device can contain data about the item, such as what the item is, what time the device travelled through a certain zone, perhaps even a parameter such as temperature. RFID devices, such as a tag or label, can be attached to virtually anything – from a vehicle to a pallet of merchandise.

RFID technology uses frequencies within the range of 50 kHz to 2.5 GHz. An RFID system typically includes the following components:

• An RFID device (transponder or tag) that contains data about an item

• An antenna used to transmit the RF signals between the reader and the RFID device

• An RF transceiver that generates the RF signals

• A reader that receives RF transmissions from an RFID device and passes the data to a host system for processing

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SCHEMATIC DIAGRAM
HOME SECURITY SYSTEM + SMS THROUGH GSM MODEM

SCHEMATIC DIAGRAM  HOME SECURITY SYSTEM + SMS THROUGH GSM MODEM

SCHEMATIC DIAGRAM HOME SECURITY SYSTEM + SMS THROUGH GSM MODEM

WE SENSE SOUND /SMOKE /OBSTACLE/ DOORS WINDOWS/ TEMP

IF ALARM IS THERE LOCAL ACTION IS THERE THROUGH RELAYS

SMS SENT THROGH GSM MODEM

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Project title is “AUTOMATIC ROOM LIGHT CONTROLLER WITH BIDIRECTIONAL VISITOR COUNTER “. mICROCONTROLLER BASED PROJECT

The objective of this project is to make a controller based model to count number of persons visiting particular room and accordingly light up the room. Here we can use sensor and can know present number of persons.

In today’s world, there is a continuous need for automatic appliances with the increase in standard of living, there is a sense of urgency for developing circuits that would ease the complexity of life.

Also if at all one wants to know the number of people present in room so as not to have congestion. This circuit proves to be helpful.


CIRCUIT DIAGRAM

Automatic room light Control with bi directional visitor counter circuit

Automatic room light Control with bi directional visitor counter circuit

RECEIVER CIRCUIT


The IR transmitter will emit modulated 38 kHz IR signal and at the receiver we use TSOP1738 (Infrared Sensor). The output goes high when the there is an interruption and it return back to low after the time period determined by the capacitor and resistor in the circuit. I.e. around 1 second. CL100 is to trigger the IC555 which is configured as monostable multivibrator. Input is given to the Port 1 of the microcontroller. Port 0 is used for the 7-Segment display purpose. Port 2 is used for the Relay Turn On and Turn off Purpose.LTS 542 (Common Anode) is used for 7-Segment display. And that time Relay will get Voltage and triggered so light will get voltage and it will turn on. And when counter will be 00 that time Relay will be turned off. Reset button will reset the microcontroller.Microcontroller based Visitor Counter.

TRANSMISSION CIRCUIT


This circuit diagram shows how a 555 timer IC is configured to function as a basic monostable multivibrator. A monostable multivibrator is a timing circuit that changes state once triggered, but returns to its original state after a certain time delay. It got its name from the fact that only one of its output states is stable. It is also known as a ‘one-shot’.

In this circuit, a negative pulse applied at pin 2 triggers an internal flip-flop that turns off pin 7’s discharge transistor, allowing C1 to charge up through

R1. At the same time, the flip-flop brings the output (pin 3) level to ‘high’. When capacitor C1 as charged up to about 2/3 Vcc, the flip-flop is triggered once again, this time making the pin 3 output ‘low’ and turning on pin 7’s discharge transistor, which discharges C1 to ground. This circuit, in effect, produces a pulse at pin 3 whose width t is just the product of R1 and C1, i.e., t=R1C1.

IR Transmission circuit is used to generate the modulated 36 kHz IR signal. The IC555 in the transmitter side is to generate 36 kHz square wave. Adjust the preset in the transmitter to get a 38 kHz signal at the o/p. around 1.4K we get a 38 kHz signal. Then you point it over the sensor and its o/p will go low when it senses the IR signal of 38 kHz.

PCB LAYOUT

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BLOCK DIAGRAM OF MICROCONTROLLER BASED MULTI STORY CAR PARKING SYSTEM PROJECT

BLOCK DIAGRAM OF MICROCONTROLLER BASED MULTI STORY CAR PARKING SYSTEM PROJECT

BLOCK DIAGRAM OF MICROCONTROLLER BASED MULTI STORY CAR PARKING SYSTEM PROJECT

DESCRIPTION


OBSTACLE SENSOR SENSING THE INCOMMING CAR
HEADLIGHT SENSING THE OUTGOING CARS
THE STEPPER MOTOR IS THERE FOR MOVEMENT OF LIFT
THREE SENSORS ARE THERE TO SENSE THE POSITION OF LIFT ON EACH FLOOR
LED 1 THROUGH 3 INDICATES ON WHICH FLOR LIFT IS LOCATED
MAXIMUM 9 CARS CAN BE PLACED ON EACH FLOOR GROUND FLOOR FIRST FLOOR AND SEC FLOOR

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INTRODUCTION

Conventionally, wireless-controlled robots use RF circuits,which have the drawbacks of limited working range, limited frequency range and limited control. Use of a mobile phone for robotic control can overcome these limitations. It provides the advantages of robust control, working range as large as the coverage area of the service provider,no interference with other controllers and up to twelve controls.Although the appearance and capabilities of robots vary vastly, all robots share the features of a mechanical, movable structure under some form of control. The control of robot involves three distinct phases: reception, processing and action. Generally, the preceptors are sensors mounted on the robot, processing is done by the on-board microcontroller or processor, and the task (action) is performed using motors or with some other actuators.

PROJECT OVERVIEW

Cell phone operated land Rover

Cell phone operated land Rover,Robot,Moving Vehicle.circuit

In this 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 of the call. This tone is called ‘dual-tone multiple-frequency’ (DTMF) tone. The robot perceives this DTMF tone with the help of the phone stacked in the robot. The received tone is processed by the ATmega16 microcontroller with the help of DTMF decoder MT8870. The decoder decodes the DTMF tone into its equivalent binary digit and this binary number is sent to the microcontroller.The microcontroller is preprogrammed to take a decision for any given input and outputs its decision to motor drivers in order to drive the motors for forward or backward motion or a turn. The mobile that makes a call to the mobile phone stacked in the robot acts as a remote. So this simple robotic project does not require the construction of receiver and transmitter units. DTMF signaling is used fr telephone signaling over the line in the voice-frequency band to the call switching centre. The version of DTMF used for telephone tone dialing is known as ‘Touch-Tone.’DTMF assigns a specific frequency (consisting of two separatetones) 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 in Table I.

SCEMATIC OF CELLPHONE OPERATED LANDROVER

Cell phone operated land rover circuit,robot,moving vehicle

Cell phone operated land rover circuit,robot,moving vehicle

CIRCUIT DESCRIPTION

Fig. 1 shows the block diagram of the microcontroller-based mobile phoneoperated land rover. The important components of this rover are a DTMF decoder, microcontroller and motor driver. 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. Table II shows the DTMF data output table of MT8870. Q1 through Q4 outputs of the DTMF decoder (IC1) are connected to port pins PA0 through PA3 of ATmega16 microcontroller (IC2) after inversion by N1 through N4,respectively. The ATmega16 is a low-power, 8-bit, CMOS microcontroller based on the AVR enhanced RISC architecture. It provides the following features: 16 kB of in-system programmable Flash program memory with read-while-write capabilities, 512 bytes of EEPROM, 1kB SRAM, 32 general-purpose input/output (I/O) lines and 32 general-purpose working registers. All the 32 registers re directly connected to the arithmetic logic unit, allowing two independent registers to be accessed in one single instruction executed in one clock cycle. The resulting architecture is more code-efficient. Outputs from port pins PD0 through PD3 and PD7 of the microcontroller are fed to inputs IN1 through IN4 and enable pins (EN1 and EN2) of motor driver L293D, espectively, to drive two geared DC motors. Switch S1 is used for manual reset. The microcontroller output is not sufficient to drive the DC motors, so current drivers are required for motor rotation. The L293D is a quad, high-current, half-H driver designed to provide bidirectional drive currents of up to 600 mA at voltages from 4.5V to 36V. It makes it easier to drive the DC motors. The L293D consists of four drivers. Pin IN1 through IN4 and OUT1 through OUT4 are input and output pins, respectively, of driver 1 through driver 4. Drivers 1 and 2, and drivers 3 and 4 are enabled by enable pin 1 (EN1) and pin 9 (EN2), respectively. When enable input EN1 (pin 1) is high, drivers 1 and 2 are enabled and the outputs corresponding to their inputs are active. Similarly, enable input EN2 (pin 9) enables drivers 3 and 4. An actual-size, single-side PCB for cellphone-operated land rover is shown in Fig. 4 and its component layout in Fig. 5.

PCB LAYOUT FOR CELLPHONE OPERATED LANDROVER

Landrover pcb Design

pcb design free

SOFTWARE DESCRIPTION

The software is written in ‘C’ language and compiled using CodeVision AVR ‘C’ compiler. The source program is ed into hex code by the compiler. Burn this hex code into ATmega16 AVR microcontroller.The source program is well commented and easy to understand. First include the register name defined specifically for ATmega16 and also declare the variable. Set port A as the input and port D as the output. The program
will run forever by using ‘while’ loop. Under ‘while’ loop, read port A and test the received input using ‘switch’ statement. The corresponding data will output at port D after testing of the received data.

WORKING

In order to control the robot, you need to make a call to the cell phone attached to the robot (through head phone) from any phone, which sends DTMF tunes on pressing the numeric buttons. The cell phone in the robot is kept in ‘auto answer’ mode. (If the mobile does not have the auto answering facility, receive the call by ‘OK’ key on the rover-connected mobile and then made it in hands-free mode.) So after a ring, the cellphone accepts the call. Now you may press any button on your mobile to perform actions as listed in Table III. The DTMF tones thus produced are received by the cellphone in the robot. These tones are fed to the circuit by the headset of the
cellphone. The MT8870 decodes the received tone and sends the equivalent binary number to the microcontroller. According to the program in the microcontroller, the robot starts moving.When you press key ‘2’ (binary equivalent 00000010) on your mobile phone, the microcontroller outputs ‘10001001’ binary equivalent. Port pins PD0, PD3 and PD7 are high. The high output at PD7 of the microcontroller drives the motor driver (L293D). Port pins PD0 and PD3 drive motors M1 and M2 in forward direction (as per Table III). Similarly, motors M1 and M2 move for left turn, right turn, backward motion and stop condition as per Table III.
CONSTRUCTION

Cellphone operated land rover project

Cellphone operated land rover project

When constructing any robot, one major mechanical constraint is the number there a two-wheel drive or a four-wheel ive. Though four-wheel drive is more complex than two-wheel drive, it provides more torque and good control. Two-wheel drive, on the other hand, is very easy to construct. Top view of a four-wheel-driven land rover is shown in Fig. 3. The chassis used in this model is a 10×18cm2 sheet made up of parax. Motors are fixed to the bottom of this sheet and the circuit is affixed firmly on top of the sheet. A cellphone is also mounted on the sheet as shown in the picture. In the four-wheel drive system, the two motors on a side are controlled in parallel. So a single L293D driver IC can drive the rover. For this robot, beads affixed with glue act as support wheels.

PROGRAM FOR CELLPHONE OPERATED LANDROVER

Source program:
Robit.c
#include
void main(void)
{
unsigned int k, h;
DDRA=0x00;
DDRD=0XFF;
while (1)
{
k =~PINA;
h=k & 0x0F;
switch (h)
{
case 0x02: //if I/P is 0x02
{
PORTD=0x89;//O/P 0x89 ie Forward
break;
}
case 0x08: //if I/P is 0x08
{
PORTD=0x86; //O/P 0x86 ie Backward
break;
}
case 0x04:
{
PORTD=0x85; // Left turn
break;
case 0x06:
{
PORTD=0x8A; // Right turn
break;
}
case 0x05:
{
PORTD=0x00; // Stop
break;
}
}
}
}

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Fire alarm circuit

Fire alarm circuit

Description.

Here is a simple fire alarm circuit based on a LDR and lamp pair for sensing the fire.The alarm works by sensing the smoke produced during fire.The circuit produces an audible alarm when the fire breaks out with smoke.

When there is no smoke the light from the bulb will be directly falling on the LDR.The LDR resistance will be low  and so the voltage across it (below .6V).The transistor will be OFF and nothing happens.When there is sufficient smoke to mask the light from falling on LDR, the LDR resistance increases and so do the voltage across it.Now the transistor will switch to ON.This gives power to the IC1 and it outputs 5V.This powers the tone generator IC UM66 (IC2)  to play a music.This music will be amplified by IC3 (TDA 2002) to drive the speaker.

The diode D1 and D2 in combination drops 1.4 V to give the rated voltage (3.5V ) to UM66 .UM 66 cannot withstand more than 4V.
Circuit diagram with Parts list.fire-alarm-circuit

 

Notes. 

  • The speaker can be a 8Ω tweeter.
  •  POT R4 can be used to adjust the sensitivity of the alarm.
  • POT R3 can be used for varying the volume of the alarm.
  • Any general purpose NPN transistor(like BC548,BC148,2N222) can be used for Q1.
  • The circuit can be powered from a 9V battery or a 9V DC power supply.
  • Instead of bulb you can use a bright LED with a 1K resistor series to it.

Lead acid battery charger circuit

Description

Here is a lead acid battery charger circuit using IC LM 317.The IC here provides the correct charging voltage for the battery.A battery must be charged with 1/10 its Ah value.This charging circuit is designed based on this fact.The charging curent for the battery is controlled by Q1 ,R1,R4 and R5. Potentiometer R5 can be used to set the charging current.As the battery gets charged the the current through R1 increases .This changes the conduction of Q1.Since collector of Q1 is connected to adjust pin of IC LM 317 the voltage at the output of of LM 317 increases.When battery is fully charged charger circuit reduces the charging current and this mode is called trickle charging mode.

Circuit Diagram with Parts List.

battery-charger.jpg

Notes .

  • Connect a battery to the circuit in series with a ammeter.Now adjust R5 to get the required charging current. Charging current = (1/10)*Ah value of battery.
  • Input to the IC must be minimum 15V to get 12 V for charging the battery .Take a look at the data sheet of LM 317 for better understanding.
  • Fix LM317 with a heat sink.

Infrared motion detector circuit

Description.

Here is the circuit diagram of an infrared motion detector that can be used to sense intrusions.Infra red rays reflected from a static object will be in one phase, and the rays reflected from a moving object will  be in another phase.The circuit uses this principle to sense the motion.

The IC1 (NE 555)  is wired as an astable multivibrator .The IR diode connected at the output of this IC produces infrared beams of frequency 5Khz.These beams are picked by the photo transistor Q1 .At normal condition ie; when there is no intrusion the output pin (7) of IC2 will be low.When there is an intrusion the phase of the reflected waveforms has a difference in phase and this phase difference will be picked by the IC2.Now the pin 7 of the IC 2 goes high to indicate the intrusion.An LED or a buzzer can be connected at the output of the IC to indicate the intrusion.

Circuit diagram with Parts list.

ir-motion-detector-circuit
Notes.

  • Comparators IC2a and IC2b are belonging to the same IC2  (LM1458).So the power supply is shown connected only once.No problem.
  • When there is disturbance in the air or vehicles passing nearby,the circuit may get false triggered.
  • POT R5 can be used for sensitivity adjustment.

Long Range FM Transmitter 1

How to make a long range FM transmitter at low cost

Description

The use of transmitters which have a more powerful output than the ‘flea-power’ are sometimes required when there are many obstacles in the path of the surveillance transmitter and monitoring station receiver, or the distance between them is too far so as to make a low powered device feasible. Whereas a typical microtransmitter will produce an RF power in the order of just a few milliwatts, i.e. a few thousandths of a watt, the VHF-FM transmitter described has a power output of between around a half and 2 watts, depending on the power source, which may be anywhere between 6 volts and 30 volts d.c. The battery or batteries should be of the alkaline high power type, since the current drain will be found to be relatively higher when compared to microtransmitter current drain. The power output of this device is somewhat proportional to the current drain and so therefore both may be decreased by altering the value of R6 to a higher resistance, or a variable resistor with a value of around 1k may be introduced in series with the existing R6, so as to give a variable power output. The variable resistor must not be a wirewound device because this would act as an inductor which will cause feedback problems.The audio input to the power oscillator, which incidentally is formed by TR2 and associated components, is derived from a piezoelectric microphone which drives the simple audio frequency amplifier TR1. The input of the audio amplifier is controlled by the gain pot R1, which selects the correct amount of voltage that is generated by the piezoelectric microphone, then connects this signal to the base of audio amplifier TR1 via C7. It may be found that there is insufficient housing space for a bulky piezoelectric microphone, so with a slight modification to the circuit, it is possible to employ an electret microphone insert as shown. Since the RF field that is generated by this transmitter is relatively large, the problem of RF feedback may very well be encountered. This may be overcome by placing the transmitter inside a metal enclosure, keeping all internal wiring as short as possible and the aerial wire.

Component listing for 1 watt transmitter

Resistors Semiconductors R1 = 27k TR1 = BC547 R2 = 330k TR2 = 2N2219 fitted with heatsink R3 = 5k6 MIC = piezoelectric microphone R4, 5 = 10k R6 = 100R

L = 6 turns 22 gauge enamelled wire wound on 3⁄16″ former

Capacitors

C1, 2, 3, 8 = 330 pF C4 = 2–10 pF trimmer C5 = 4p7 C6 = 1 nF

C7,C8 = 40uF/25V Electrolytic

Circuit diagram for Long range FM Transmitter

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