Door Open Sensor

Each Door Open Sensor is made up of two parts. A magnet and a switch. The magnet will be attached to the door. The switch will be attached to the door frame. Depending on the relative position of magnet and switch, the switch will open or close. With the proper placement, this will allow the detection of the door being opened or closed Once the switch is wired to an input of the Frotcom GPS/GPRS device; these changes will be detected and communicated to the Frotcom Data Center. Then, Frotcom will update the door open status for that vehicle and check for alarm conditions.

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Main features

Here are some of the main features of the Door Open Sensor:

• Thermoplastic enclosure
• Flat design
• Long life
• Non-contacting principle
• 1 reed contact
• Actuating distance up to 60mm
• Actuating surface marked by protrusion
• Pre-wired cable with length 1m
• Protection class IP 67

BURGLAR ALARM

               

A burglar alarm is a system designed to detect intrusion – unauthorized entry – into a building or area. They are also called security alarms, security systems, alarm systems, intrusion detection systems, perimeter detection systems, and similar terms.

Burglar alarms are used in residential, commercial, industrial, and military properties for protection against burglary (theft) or property damage, as well as personal protection against intruders. Car alarms likewise protect vehicles and their contents. Prisons also use security systems for control of inmates.

Some alarm systems serve a single purpose of burglary protection; combination systems provide both fire and intrusion protection. Intrusion alarm systems may also be combined with closed circuit television surveillance systems to automatically record the activities of intruders, and may interface to access control systems for electrically locked doors. Systems range from small, self-contained noisemakers, to complicated, multi-area systems with computer monitoring and control.

GAS SENSOR MQ-6

Whenever there is LPG concentration of 1000 ppm (parts per million) in the area, the OUT pin of the sensor module goes high. This signal drives timer IC 555, which is wired as an a stable multivibrator. The multivibrator basically works as a tone generator.

Output pin 3 of IC 555 is connected to LED1 and speaker-driver transistor SL100 through current-limiting resistors R5 and R4, respectively. LED1 glows and the alarm sound to alert the user of gas leakage. The pitch of the tone can be changed by varying preset VR1. Use a suitable heat-sink for transistor SL100.

 

Gas Sensor MQ-6

 FEATURES

High sensitivity to LPG, ISO-butane, propane

Small sensitivity to alcohol, smoke.

Fast response.

Stable and long life

Simple drive circuit

APPLICATION

They are used in gas leakage detecting equipments in family and industry, are suitable for detecting of LPG, ISO-butane, propane, LNG, avoid the noise of alcohol and cooking fumes and cigarette smoke.

TEMPERATURE SENSOR LM35

General description of  LM 35

The LM35 is an integrated circuit sensor that can be used to measure temperature with an electrical output proportional to the temperature (in ^oC) The LM35 series are precision integrated-circuit temperature sensors, whose output voltage is linearly proportional to the Celsius (Centigrade) temperature. The LM35 thus has an advantage over linear temperature sensors calibrated in ° Kelvin, as the user is not required to subtract a large constant voltage from its output to obtain convenient Centigrade scaling. The LM35 does not require any external calibration or trimming to provide typical accuracies of ±1⁄4°C at room temperature and ±3⁄4°C over a full −55 to +150°C temperature range. Low cost is assured by trimming and calibration at the wafer level. The LM35’s low output impedance, linear output, and precise inherent calibration make interfacing to readout or control circuitry especially easy. It can be used with single power supplies, or with plus and minus.

                                                           

LM 35 Temperature Sensor 

                                                      

Features

1.      Calibrated directly in ° Celsius (Centigrade)

2.      Linear + 10.0 mV/°C scale factor

3.      0.5°C accuracy guarantee able (at +25°C)

4.      Rated for full −55° to +150°C range

5.      Suitable for remote applications

6.      Low cost due to wafer-level trimming

7.      Operates from 4 to 30 volts

8.      Less than 60 μA current drain

9.      Low self-heating, 0.08°C in still air

10.  Non linearity only ±1⁄4°C typical

11.  Low impedance output, 0.1 W for 1 mA load

 Advantages of LM35  to Measure Temperature?

You can measure temperature more accurately than a using a thermistor.  

The sensor circuitry is sealed and not subject to oxidation, etc.

The LM35 generates a higher output voltage than thermocouples and may not require that the output voltage be amplified.

Working of LM35:

The scale factor is .01V/^oC. 

The LM35 does not require any external calibration or trimming and maintains an accuracy of +/-0.4 ^oC at room temperature and +/- 0.8 ^oC over a range of 0 ^oC to +100 ^oC.

Another important characteristic of the LM35DZ is that it draws only 60 micro amps from its supply and possesses a low self-heating capability. 

The sensor self-heating causes less than 0.1 ^oC temperature rise in still air. 

It has an output voltage that is proportional to the Celsius temperature. 

All About Electronics: Advantages of optical fiber communication

All About Electronics: Advantages of optical fiber communication: Let us see the advantages of optical fiber communication over conventional communication system  Enormous bandwidth: the informati...

Advantages of optical fiber communication

Let us see the advantages of optical fiber communication over conventional communication system 

Enormous bandwidth: the information carrying capacity of a transmission system is directly proportional to the carrier frequency of the transmitted signals. The optical carrier frequency is in the range of 10^14Hz while the radio frequency is about 10^6Hz. Thus the optical fibers have enormous transmission bandwidth and high data rate. Using wavelength division multiplexing operation, the data rate or information carrying capacity of optical fibers is enhanced to many orders of magnitude.

Low transmission loss: due to the usage of ultra low loss fibers and the erbium doped silica fibers as optical amplifiers, one can achieve almost loss less transmission. Hence for long distance communication fibers of 0.002dB/km are used. Thus the repeater spacing is more than 100km. 

Immunity to cross talk: since optical fibers are dielectric wave guides, they are free from any electromagnetic interference (EMI) and radio frequency interference (RFI). Since optical interference among different fibers is not possible, cross talk is negligible even many fibers are cabled together. 

Electrical isolation: optical fibers are made from silica which is an electrical insulator. Therefore they do not pick up any electromagnetic wave of any high current lightening. It is also suitable in explosive environment.

Small size and weight: the size of the fiber ranges from 10 micrometers to 50 micrometers which is very small. The space occupied by the fiber cable is negligibly small compared to conventional electrical cables. Optical fibers are light in weight. These advantages make them to use in aircrafts and satellites more effectively.

Signal security: the transmitted signal through the fiver does not radiate. Unlike in copper cables, a transmitted signal cannot be drawn from a fiber without tampering it. Thus, the optical fiber communication provides 100% signal security. 

Ruggedness and flexibility: the fiber cable can be easily bent or twisted without damaging it. Further the fiber cables are superior than the copper cables in terms of handling. Installation, storage, transportation, maintenance, strength and durability.

Low cost and availability: since the fibers are made of silica which is available in abundance. Hence, there is no shortage of material and optical fibers offer the potential for low cost communication.

Reliability: the optical fibers are made from silicon glass which does not undergo any chemical reaction or corrosion. Its quality is not affected by external radiation. Further due to its negligible attenuation and dispersion, optical fiber communication has high reliability. All the above factors also tend to reduce the expenditure on its maintenance.

Basic structure of optic fiber cable

Basic structure of optic fiber cable

                                               

An optical fiber can be called as a dielectric waveguide. This waveguide operates at optical frequencies.

The fiber consists of three parts namely

1.       Core

2.       Cladding and

3.       Buffer coating

The core of the fiber is cylindrical and has a radius a. its refractive index is represented by n1.

The core is surrounded by a solid dielectric cladding whose refractive index is n2. The refractive index of the core n1 is always greater than the refractive index of cladding n2. The cladding gives mechanical strength to the inner core.

The buffer coating gives additional strength and prevents any damage to the fiber.

Since the cladding that surrounds the core has lower refractive index than the core, the light is guided through the core due to total internal reflection.