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MEASURING OF TEMPERATURE

MEASURING OF TEMPERATURE:
For measuring the temperature of the body, a temperature sensor LM 35 is used. The LM35 are accurate combined circuit temperature sensor, whose output voltage is linearly proportional to the Celsius temperature. It can be worked with single supply or terminal power supplies. It draws only 60 µA from its power supply which results the low self heating. The LM35 is operated at a temperature range over a -55° to +150°C. The LM35 doesn’t need any exterior calibration provide typical exactness of ±1.4°C at room temperature and ±3.4°C over a full -55 to +150°C temperature range.
The output from the temperature sensor is fed to the Op-Amp LM 324. Description about this Op-Amp is provided in the alcohol sensing circuit. The cut off temperature value is set at the reference pin of the Op-Amp and the sensor input is fed to the other pin of the Op-Amp. Now the Op-Amp will compare the input temperature value with the cut off value set as the reference value and will provide a high signal to the controller when the value exceed the cut off value indicating high temperature to the driver.
EYE BLINK SENSOR:
The block is designed using IR Sensors. The eye blink-sensing block is designed with LM567 IC, this is a tone decoder IC, and also it generates tone frequency. The sensing block is designed with infrared sensors; a set of IR sensors are used as IR signal transmitting LED and IR signal receiving LED. These sensors are arranged side by side and are mounted in front of the eye. Both the sensors are wired with IC 567, this is a tone frequency generator cum decoder IC, means this IC can produce a tone frequency of up to 20 KHz, and the same IC also can decode the frequency. Since this IC can perform two different functions, the IR signal transmitting LED is connected at the output of tone signal generating part of IC, similarly the IR signal receiving LED is connected at the output of tone signal decoding part of IC. The tone signal generating part is configured as free running oscillator, with the help of a resistor and capacitor connected externally to this oscillator frequency can be adjusted. When the circuit is energized it starts producing a continuous chain of square pulses. The output of this oscillator is amplified and fed to IR LED. This LED radiates the signal in to air and depending up on the signal strength or radiating power, the range can be increased. The IR signal delivered from the IR LED transmitted in a line like a laser beam, this beam is invisible and harmless. When the transmitted laser beam interrupted by closing of the eye, this beam will be disturbed by the object and some of the signal will be reflected, this reflected signal will be received by the receiver infrared LED. The output of IR-Receiver is (proportional to reflected wave) found for matching (comparing) with that of transmitted wave, and then the output of the IC will becomes low automatically (If both are equal then output of this IC becomes low). The output of this tone decoder IC is fed to microcontroller.
The basic function of the detector circuit is by radiating energy into space through IR LED and detecting the echo signal reflected from an object. The reflected energy that is returned to the IR sensor indicates the presence of an object which is within the range. A part of the transmitted energy is intercepted by the target and re-radiated in many directions. The radiation is given back towards the system that is collected by the receiving LED which causes to produce a high signal at Pin No.8 of LM567 IC. The output of the receiver is fed to the microcontroller.
BRAKE OPERATION:
A small push to ON switch is interfaced with microcontroller, for giving the input that the break is applied; this key has to be activated to apply the break. In addition two more such switches are used to demonstrate the vehicle speed movement that is shown by the operation of a DC motor. By pressing one button the motor will be rotated at high speed indicating the vehicle moving at over speed and the other button to indicate normal speed at which the motor will be rotating at lower speed.
WATER (WET ROAD) SENSING:
To find the wetness an electronic circuit is designed, which takes care of the monitoring of water (wet road) continuously. For this, two electrodes are used. One electrode is fed with +5V DC and the other electrode is used for indicating the sensitivity of the road to the micro controller. When the road is completely dry, the electrode will be in open circuit condition. Since water is a conductor of electricity, whenever the road becomes wet, conduction makes continuity between the conductors (electrodes) and a logic high signal will be received by the controller if water is detected. The output of sensing electrode is fed to microcontroller and according to the high/low signals from the electrode; the microcontroller senses the road condition wet or dry.