Infrared Sensor

Sensors are everywhere, some examples:

* Smaller shops or barbershops, often have a beam of light crossing the room near the door, which ends up in a photo-sensor on the other side of the room. When a customer breaks that beam, the bell rings.

* Bigger markets have automated doors, the black bulb above the door sends a burst of microwave radio energy, and waits for the reflected energy to bounce back. When a person walks into that field, the amount of energy is changed,...resulting in the door to open. Therefor you can't just run in a market, the doors wont open fast enough ;). So no kidz, it doesn't have a little leprecon in it, which presses a button to open the doors!!


* Same thing with ultrasonic sound waves used by bats for example, they bounce back off a target and create an image.
These are what we call active sensors. They send out energy, and detect changes in them .


Motion Sensor

The motion sensing system is a passive sensor. It detects infrared energy. Human beings have a skin temperature of approximately 36° Celsius or 93° Fahrenheit, this produces an infrared energy with a wavelength between 9 and 10 micrometers. When infrared energy is detected, that infrared light bumps electrons of the sensors substrate, these are amplified and result in a signal.
People who have these little sensors, may notice that the sensing light doesn't go off when you're standing still. That's because the sensor is programmed to sense rapidly changes, you don't want every change of infrared light setting off the alarm .

If you're searching for a hack in this system, ...than this is your lucky day, because you can. The sensors are sensitive in a range of 8 - 12 micrometers. So all you need to do is calculate what body temperature you got to have to produce waves of 7 micrometers or less. I'm not responsible if you got hypothermia afterwards ;) . Or maybe you could build a glass bulb around you, glass doesn't let the infrared waves through, think of a greenhouse, the light goes in , but then it's trapped inside... so beware of people passing by in the possession of glass bulbs...

Footnote: During Operation: Desert Storm. The US military used infrared vision equipped tanks to spot and fight hostile tanks at night. Result: hostile tanks getting slaughtered like a sitting duck, technology = win
About the Author:

I'm Jan Vansteenlandt, i'm 19 years old, i still attend school.

My articles will be around the technology topic, and all it's subcategories. Normally IT-related.

I hope you enjoy them :)

Article Source: http://www.articlesbase.com/electronics-articles/infrared-sensor-544013.html

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Speed Sensors of Turbine

With turbine technology finding its way into more and more aspects of todays high tech world, many people just like yourself may find themselves in uncharted water in having to deal with them. The fact is, that turbines can be simple or extremely complex depending on what they are used in.

A Complex Turbine

For instance, a modern jet will have a highly complex turbine engine that burns fuel inside a series of alloy fan bladed to generate thrust. This would be a highly complex example of a turbine system being used to generate kinetic energy and force.

A Simple Turbine Engine

At the same time, the simple spinning vent on the roof of a house is yet another example of a far more simpler turbine engine. Even though it has only one moving part, it is by definition, a turbine engine none the less. Heat in the attic carries the energy that powers the roof vent turbine to spin, causing it to suck air out of the attic, thereby ventilating it.

Turbine Speed Indicators

A turbine speed sensor is but one of the many types of sensors that would be found on a complex turbine engine. Why is it necessary to know the speed that a turbine in an engine is spinning? If the engine is a jet engine, the the turbine is the main power source and the speed that it is rotating would be a prime indicator propulsion.

Turbo Charged Air Intake Systems

Also, a turbine can be an integral part but not the main component of a propulsion system or engine. A prime example of this would be a car with a turbo charged intake system. In this case a turbine speed sensor would provide real time information on how the air intake system is functioning at any given time.

Article by Rosa Telipten. Here you will find everything you wanted to learn regarding Turbine Speed Sensor and even Magnetic Speed Sensors

Article Source: _http://EzineArticles.com/?expert=Rosa_Telip_Ten

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Optoisolators

Optoisolators are circuits designed to isolate one circuit from another using light. Why would you use light instead of implementing some diodes or voltage regulators? Because light is essentially a guaranteed protection. If an overvoltage or overcurrent is applied to the optoisolator, the optoisolator circuit is destroyed and the circuit(s) it was protecting will not be affected.

The most common optoisolators are placed in an integrated circuit for convenience and efficiency. The most popular model is the 4N33, which is housed in an 8-pin DIP package. The 4N33 internally is basically an LED next to a phototransistor. This could be called an optical modem, since it modulates the electric signal into light waves, which are demodulated by the phototransistor as it converts the light into electricity again.

To design a circuit using an optoisolator, you cannot ignore the components inside of it. On the input circuit, you must take the forward voltage of the LED into account, which can be approximated to .7 volts. On the output side, you should take the phototransistor's forward voltage into account and it can be approximated to .2 volts. If you are working with relatively high voltages, you will need a resistor on the input to protect the LED.

Optoisolators are commonly used to protect expensive circuits from voltage and current surges. One example application would be on the output of a microprocessor. Most microprocessors can't output a very high current, but you might want to be able to power a motor with an output pin. To work around this problem, you could connect the output pin to the optoisolator's input and then connect the motor in series with the output and a voltage supply that is high enough to power the motor. This way, the majority of the current is coming from the independent power supply rather than the microprocessor.

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