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Interesting Technologies to Build a Project Around
Transducers
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Thermo-Electric (TE) Devices: Peltier junction devices in a series string packaged as a
sandwich in between ceramic sheet layers. Anodes to one side, cathodes to the other, the
device is capable of creating thermal energy (hot side and cold side) for many
applications including electronic cooling, refrigeration, heating. The devices are
typically driven with a thermal feedback control system and a variable controlled DC
current source.
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Photo Voltaic Cells: Also known as solar cells, in single cell form these devices deliver
approximately 1.2V and an output power proportional to their total cell area and the
intensity (flux) of the impending light photons striking their surface. Usually constructed
from single and poly crystal silicon, they can also be manufactured using amorphous
technology such as cadmium telluride. Devices are typically series connected for higher
voltages. This technology will start to appear more frequently in consumer applications
as the cost of commercially generated electricity continues to rise. Most commonly seen
as power sources for small electronics such as calculators, watches they are now
becoming common for small battery or storage capacitor charging applications.
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Peizo-Electric Devices: Available as films and crystalline devices, this technology uses
the peizo-electric effect in which a material exhibits a small voltage when put into
compression. Some devices are engineered to take advantage of the effect in a biased
condition to allow detection of small pressure or create oscillation circuits.
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RFID’s: This is typically a small packaged device which contains antenna, receiver,
transmitter and a small amount of logic. The device responds to an incoming RF signal
from a compatible “reader” and sends back a predefined code. There are many types and
ranges of this technology which is rapidly decreasing in cost. Many RFID tags are
available on a tape reel now.
Sensors
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Thermal: Thermocouple and Thermistors are available alone or as a system which
includes drive, sensing, linearization and digitization circuitry. Stand alone sensors are
typically available with mechanical housing enabling them to thread into pipes, tanks,
vessels, chassis, heat sinks and other structures. Sensors with processing circuitry are
typically available in IC form or small PCB mountable packages.
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Humidity: One of the more complex sensors types, they typically employ a small
system which contains a polymer resin used as the dielectric of a capacitor designed to
expand and contract with moisture. As the capacitance changes, it is detected by a
sensing circuit which contains an oscillator driver and a rectification filter circuit. The
DC voltage may then be scaled and linearized before made available as an output or it
may be digitized and sent out as serial data.
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Pressure: Also made with peizo-electric effect and available as small IC packaged form.
Larger pressure sensors are made with mechanical housings in a threaded form to be
inserted into pipes and vessels. Some sensors are designed for gas or air pressure, others
are designed for sensing liquid pressures. Pressure sensors can also be constructed with
LVDT and other transducer technology.
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Light: Cadmium Sulfide Photocell, Phototransistor, Photodiode are all common forms
of light sensors used for various applications. Photodiodes act as tiny current sources
and are usually reverse biased which allows them to deliver more photo-electric gain or
electrons out vs photons in. These devices are usually interfaced using a very high gain
and high speed transimpedance amplifier. Phototransistors can be constructed as
standard transistors but with based current drive from a photodiode structure on the Si die
of the transistor. Lower noise in the signal can be achieved because there is very little
interconnect capacitance when devices are integrated on the same die. Photocells are
really resistance that change impedance when light photos strike their sensing surface.
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Radiation: There are many types of radiation sensors devices available that offer
sensing of X-Ray, Gamma Ray, Beta and Alpha particle radiation detection. However
these devices usually fall into 1 of 2 categories. The first is known as an indirect
conversion in which the radiation photons strike a material that has scintillation
properties which allows it to convert the incoming radiation into visible light and heat.
The scintillation material is mounted directly above a light sensing photodiode which
then in turn generates small current proportional to the radiation flux. The second type of
sensor is known as a direct conversion sensor in which a special material under bias
generates small current when radiation photons strike and terminate within the material.
Direct conversion sensors typically have higher photo-electric gains than indirect
however they usually require high bias voltages to operate effectively. Both types of
sensors are energy sensitive and care must be taken to make sure the sensor is well
matched for the particular radiation spectrum and type being sensed.
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Acceleration: Typically peizo-electric effect based, these devices are now available in
small packaged IC form to detect direction and G force acceleration
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Strain or Tensile Force: Typically a small resistor formed on a flat paper or plastic
substrate this device is adhesively attached to a structural load bearing member usually
metallic. As the member is tensioned or compressed, the impedance of the strain gauge
changes and must be sensed by a calibrated drive and readout circuit which usually
contains an instrumentation amplifier circuit.
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Ph: These temperature sensitive devices usually deliver a small change in output voltage
or current with respect to changing acidity of solutions they are sensing. They are usually
coupled with a temperature sensor to allow proper calibration of the Ph sensor.
Links to Interesting Electronics Project Ideas, Kits, Components and Tutorials Sites:
(Please let us know if any of these do NOT work so we may update)
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http://www.web-ee.com/
http://www.electro-tech-online.com/
http://www.hallbar.com/
http://www.electronics-lab.com/
http://www.electronickits.com/
http://www.proaxis.com/~iguanalabs/micropro.htm
http://my.integritynet.com.au/purdic/
http://www.knowledgehound.com/topics/electron.htm
http://www.juliantrubin.com/electronicsprojects.html
http://www.electronicsforu.com/electronicsforu/top100/top100electronics.asp
http://ee.cleversoul.com/projects.html
http://www.hvwtech.com/pages/default.asp
http://dir.yahoo.com/Recreation/Hobbies/Electronics/
http://electronicsusa.com/
http://www.uoguelph.ca/~antoon/circ/circuits.htm
http://www.amasci.com/amateur/elehob.html
http://www.hobbytron.com/electronickits.html
http://www.siliconchip.com.au/menu_1599/section_articles/cms/section.html
http://www.ce.ucsb.edu/senior%20elective%20descriptions.htm#ECE
http://www.cet.nau.edu/Academic/Design/D4P/Projects/486-projects.htm
Other University Capstone Project Sites:
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http://services.eng.uts.edu.au/~gdissa/capstone/
http://www.msoe.edu/library/mse/
http://ctas.east.asu.edu/post/capweb/projdir.htm
http://www.cs.washington.edu/info/videos/
http://www.cet.nau.edu/Academic/Design/D4P/Projects/486-projects.htm - ee
http://www.isu.edu/engineer/srdesign.html
http://doc.union.edu/cse/capstone_projects.html
http://scpm.ltc.arizona.edu/projects/
http://www.coe.neu.edu/Depts/SET/set/capstone.html
http://www.ece.ualberta.ca/~ee401/index.html
http://www.eng.lsu.edu/news_events/news.stories/students.capstoneII.html
http://www.seas.virginia.edu/news/context.php
http://ece-www.colorado.edu/academics/ug/expo.html
http://engineering.lssu.edu/Students/seniors.html
http://www.uidaho.edu/engr/ME/sr_des/
http://www4.nau.edu/insidenau/bumps/5_4_05/capstone.htm
http://www.widener.edu/Academics/Schools_amp_Colleges/School_of_Engineering/Curr
ent_Students/Undergraduate_Programs/Senior_Projects/1525
General Science Project and Hobby Interest Sites:
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http://www.exploratorium.edu/
http://www.einsteins-emporium.com/science/l-optics/sl210.htm
http://www.explorescience.com/index.cfm
http://www.ipl.org/youth/projectguide/
http://www.mcrel.org/whelmers/
http://www.isd77.k12.mn.us/resources/cf/
http://www.eskimo.com/~billb/
http://scienceclub.org/scifair.html