Outline

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IntroductionIn today’s business environment, the US sensor

market is expected to grow at an annual rate of

4.6%, to reach approximate $7.6 billions by 2009.

Increased sensor demand will bring an increase

in production and testing capacity.

Our objective is to design a tool and establish its

technical requirements, in order to speed up the

testing of sensors in the manufacturing process.

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BackgroundSensor is a device that responds to a physical stimulus,

such as thermal energy, electromagnetic energy,

acoustic energy, pressure, or motion, by producing an

electrical signal.

Most sensors are electrical or electronic although other

types exists.

Electrical voltage sensors vary in terms of performance,

specifications, optional features and environmental

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System DescriptionThe system described will focus on testing electrical

voltage sensors and all tests are assumed to be done at

room temperature.

The system will test newly built sensors and compare it

against a reference sensor known as a “good” sensor.

The testing tool will lit a green light for a “Pass” unit

and a red light for a “Fail” unit.

The system consists of four stages: differential stage,

rectifier stage, comparator stage, and selection stage.

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System Diagram

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Design

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1. Differential Block

Potentiometers are used

to simulate the sensors

Upper POT is the tested

sensor

Lower POT is the

reference sensor

Difference between two

sensors is amplified (Gain

= 30)

The difference can be

either positive or negative

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2. Rectifier Block

The input to the rectifier

could either be positive or

negative.

The purpose of the

rectifier is to take the

absolute value of the input

voltage.

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3. Comparator Block

The absolute value of the

difference is compared to

the threshold voltage.

The threshold voltage

can be adjusted according

to our specifications.

The output can either be

positive or negative.

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4. Selection Block (Pass)

If the input voltage is

negative, Q1 is cut-off, Q2

is in the active region.

Green LED lights up

which indicates the sensor

passed the test.

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4. Selection Block (Fail)

If the input voltage is

negative, Q2 is cut-off, Q1

is in the active region.

Red LED lights up which

indicates the sensor failed

the test.

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Selection Range

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Selection Range (2)

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Future DevelopmentDevelop the testing tool such that other types of

sensors can be tested.

The testing tool can be made portable, so that it

can be used in different locations.

Digital display can also be added for input and

output observations.

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ReferencesBelusov, Alex “Simple procedure test transducer” EDN, March 1, 1996, pg 144

Frank Keys, “All Types of Sensors”,

http://www-sensors.com/sensors-applications.html

Sensorsoft Corporation, “Real-time Contract and Voltage Sensor

Specifications’’, 2005-2006

Wikipedia, Sept. 2006, http://en.wikipedia.org/wiki/Sensors

Telecom Glossary 2K,

Feb.2001, http://www.atis.org/tg2k/_sensor.html

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