Sharp GP2DXX Infrared Detectors

Over the years, Sharp has introduced a range of precision infra-red detectors. These detectors boast a small package, very little current consumption,and a variety of output options.Recently found one good web article offers an overview of the various types, information on interfacing them, and hints and tips.

With the introduction of the GP2DXX line of Sharp detectors, a new approach was developed that not only gives object detection at a longer range than the previous method, but also offers range information, in the case of the GP2D12, GP2D120, and GP2DY0A ('0A') detectors. These new rangers offer much better immunity to ambient lighting conditions because of the new method of ranging.

These new rangers all use triangulation and a small linear CCD array to compute the distance and/or presence of objects in the field of view. The basic idea is this: a pulse of IR light is emitted by the emitter. This light travels out in the field of view and either hits an object or just keeps on going. In the case of no object, the light is never reflected and the reading shows no object. If the light reflects off an object, it returns to the detector and creates a triangle between the point of reflection, the emitter, and the detector.

The angles in this triangle vary based on the distance to the object. The receiver portion of these new detectors is actually a precision lens that transmits the reflected light onto various portions of the enclosed linear CCD array based on the angle of the triangle described above. The CCD array can then determine what angle the reflected light came back at and therefore, it can calculate the distance to the object.



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Semiconductor Combustible Gas Sensor MQ-2

How to design and fabricate a reliable Combustible Gas Detector Alarm using easy to use and inexpensive components?One good answer to the question is MQ-2.Yes,we can build such a useful circuit (suitable for detecting of LPG, i-butane, propane, methane ,alcohol, Hydrogen,smoke) using the MQ-2 Semiconductor Gas Sensor!

MQ-2 is a Semiconductor Sensor for Combustible Gas.MQ-2 gas sensor has high sensitity to LPG, Propane and Hydrogen, also could be used to Methane and other combustible steam, it is with low cost and suitable for different application.Sensitive material of MQ-2 gas sensor is SnO2, which with lower conductivity in clean air. When the target combustible gas exist, The sensor’s conductivity is more higher along with the gas concentration rising.Just use simple electrocircuit, Convert change of conductivity to correspond output signal of gas concentration.

Features of MQ-2

*Good sensitivity to Combustible gas in wide range

* High sensitivity to LPG, Propane and Hydrogen

* Long life and low cost

Application of MQ-2

* Domestic gas leakage detector

* Industrial Combustible gas detector

* Portable gas detector

Basic test circuit of the sensor is shown here.The sensor need to be put 2 voltage,heater voltage(VH) and test voltage(VC).VH used to supply certified working temperature to the sensor, while VC used to detect voltage (VRL) on load resistance (RL)whom is in series with sensor. The sensor has light polarity, Vc need DC power. VC and VH could use same power circuit with precondition to assure performance of sensor. In order to make the sensor with better performance, suitable RL value is needed: Power of Sensitivity body(Ps): Ps=Vc2×Rs/(Rs+RL)2.

MQ-2 sensor is composed by micro AL2O3 ceramic tube, Tin Dioxide (SnO2) sensitive layer, measuring electrode and heater are fixed into a crust made by plastic and stainless steel net. The heater provides necessary work conditions for work of sensitive components. The enveloped MQ-2 have 6 pin, 4 of them are used to fetch signals, and other 2 are used for providing heating current.

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Hall Effect Sensor IC- MH183

Hall Sensor IC is not a familiar component to many electronic hobbyists.The Hall-Effect principle is named for physicist Edwin Hall. In 1879 he discovered that when a conductor or semiconductor with current flowing in one direction was introduced perpendicular to a magnetic field a voltage could be measured at right angles to the current path.

Now Hall Sensor ICs are widely available at very reasonable rates and it is easy to design interesting circuits using such tiny chips.Here is the data of MH183-one popular CMOS Unipolar Hall Switch from MST.

MH 183 is a unipolar Hall effect sensor IC. It incorporates advanced chopper stabilization technology to provide accurate and stable magnetic switch points. The design, specifications and performance have been optimized for applications of solid state switches. The output transistor will be switched on in the presence of a sufficiently strong South pole magnetic field facing the marked side of the package. Similarly, the output will be switched off in the presence of a weaker South field and remain off with “0” field.

Features and Benefits

• CMOS Hall IC Technology
• Solid-State Reliability
• Chopper stabilized amplifier stage
• Unipolar, output switches with absolute value of South pole from magnet
• Operation down to 2.5V
• High Sensitivity for direct reed switch replacement applications
• Small Size in TO 92S or Sot 23 package.
• Custom sensitivity / Temperature selection are available.

Applications

• Solid state switch
• Limit switch
• Current limit
• Interrupter
• Current sensing
• Magnet proximity sensor for reed switch replacement in low duty cycle applications

Absolute Maximum Ratings

• Supply Voltage (Operating), VDD 28V
• Supply Voltage (Reverse) VDD -0.3V
• Supply Current (Fault), IDD 50mA
• Output Voltage, VOUT 24V
• Output reverse Voltage, VOUT -0.3V
• Output Current (Fault), IOUT 50mA

Warning: Do not apply reverse voltage to VDD and VOUT Pin, It may be caused for Malfunction or damaged device.

For more about Hall Sensors CLICK HERE