Supply Lab Tube Math Question Please help. 10 points!?
Dan orders supplies for a science lab. Each of the 24 stations in the chemistry lab needs 2 feet of rubber tubing. If rubber tubing sells for $8.75 per yard, how much will it cost to equip?
Black and White Phlebotomy Tray Tray with Red Handle Four large customizable compartments with removable white dividers. Constructed of lightweight, easy-to-clean ABS plastic. Sturdy aluminum handle has vinyl hand grip. All measure 16.5"?L x 11.5"?W x 9.5"?H. Organize all your phlebotomy supplies in style. Includes a 90-place 13mm tube rack . 4 long dividers. 6 short dividers. Tube rack (13mm or 17mm). Memo clipboard.
Voodoo Labs Pedal Power AC, Power all your pedals from a single source! The Voodoo Labs Pedal Power AC is a pedalboard power supply designed to operate high current and AC powered pedal effects. Finally, a professional solution for powering tube overdrives, modeling pedals, or devices including the Whammy, POD, Rotosphere and many others without bulky wall wart power supplies. The Pedal Power AC provides two 9VAC and two selctable 9VAC or 12VAC outputs, features include a toroidal transformer and completely isolated outputs to ensure noise free operation. It comes complete with cables and a detachable AC power cord.
Features of Lab Safety Supply Oversleeves: Lightweight, rubber-coated cloth moves with you for comfort. Oversleeves keep forearms covered. 15"L with elastic wrists and tops. Gray.
Features of the BD Sterile Venous Blood Collection Tube: 13 x 100 mm x 4.5 mL BD Vacutainer® Plus plastic plasma tube. Light Green BD Hemogard™ closure. Paper label. Additive: Lithium heparin (spray coated) and polymer separator gel. BD Vacutainer® brand sterile chemistry tubes with the BD Hemogard™ closure help to protect lab personnel from contact with blood on the stopper or around the outer rim of the tube, as well as from blood splattering upon opening the tube. The rubber stopper is recessed inside the plastic shield, so any drops left by a blood collection needle remain isolated from potential contact.
Features of the BD Sterile Venous Blood Collection Tube: 13 x 100 mm x 5.0 mL BD Vacutainer® Plus plastic serum tube. Gold BD Hemogard™ closure. Paper label. Additive: Clot activator and gel for serum separation. Silicone coated interior. BD Vacutainer® brand sterile chemistry tubes with the BD Hemogard™ closure help to protect lab personnel from contact with blood on the stopper or around the outer rim of the tube, as well as from blood splattering upon opening the tube. The rubber stopper is recessed inside the plastic shield, so any drops left by a blood collection needle remain isolated from potential contact.
Features of the Level1 Snuggle Warm Blankets: Snuggle Warm® Tube Blanket provides coverage around the patient and is ideally suited for procedures done in the Cath-Lab in order to give clinician the full access they need to the patients entire body. Snuggle Warm® blankets are designed for effective and safe patient warming and comfort. Made fabric-like material that is soft and comfortable yet durable resisting tears, punctures and fluids. Designed with safety in mind, the air hole perforations are custom placed to ensure effective heat delivery reducing the risk of hot spots. Easy to use and manipulate - can be folded or repositioned for quick patient access. Conforms to the patient’s body with no billowing- eliminating the need to tie down or secure the blanket. Hose to blanket retaining mechanism firmly secures hose to blanket. Radio-translucent material will not interfere with x-rays. Meets flammability standards NFPA 702 and 16 CFR 1610. CE marked.
Features of the Lab Safety Supply Lightweight Cloth Apron: Lightweight, rubber-coated cloth apron moves with you for comfort. Splash Protection cloth apron has cotton ties at the neck and waist plus reinforced stress points.
Features of the Lab Safety Supply Lightweight Cloth Apron: Lightweight, rubber-coated cloth apron moves with you for comfort. Splash Protection cloth apron has cotton ties at the neck and waist plus reinforced stress points.
Features of the Lab Safety Supply Lightweight Cloth Apron: Lightweight, rubber-coated cloth apron moves with you for comfort. Splash Protection cloth apron has cotton ties at the neck and waist plus reinforced stress points.
Features of the Lab Safety Supply Lightweight Cloth Apron: Lightweight, rubber-coated cloth apron moves with you for comfort. Splash Protection cloth apron has cotton ties at the neck and waist plus reinforced stress points.
Features of the Lab Safety Supply Lightweight Cloth Apron: Lightweight, rubber-coated cloth apron moves with you for comfort. Splash Protection cloth apron has cotton ties at the neck and waist plus reinforced stress points.
The Voodoo Lab Tremolo Pedal incorporates the same cicuitry found in vintage tube amps to achieve an authentic vintage tone. This Tremolo's Speed and intensity controls provide a wide range to include very slow and exceptionally deep sounds. It also features a slope control which lets you adjust the feel from traditional to a hard on/off stutter. The Tremolo is housed in a sturdy aluminum case and features a heavy duty metal switch, true bypass and an LED status indicator. All Voodoo Lab products are hand made in the U.S.A. and carry a 5-year warranty. Voodoo Lab guitar effect pedals are faithful recreations of the most sought after pedals of the '60s and '70s. Handcrafted from the finest modern and vintage components, these pedals are housed in rugged, die cast aluminum cases with heavy duty metal switches. All Voodoo Lab guitar effects are 100% analog, handwired, and feature true bypass switching. Nicely voiced, with very slow and very fast speeds... -Guitar Player The Voodoo Lab Tremolo re-creates the buttery, seductive tone of a vintage tube amp tremolo. This is accomplished by using the same lamp and photocell assembly found in many popular vintage amps. This pedal also features a slope control which lets you adjust the feel from a traditional soothing tremolo to a hard machine-gun stutter. Speed and intensity controls provide a wide range to include very slow and deep sounds. A volume control lets you cut or boost the output level. Now you can add warm, mind-bending trem vibes to any amp with the most versatile tremolo available.
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Electronics Lab
Dog cough question?
My female 3 year old lab/dalmation got spayed on Thursday. They had a tube down her throat to supply oxygen. When she woke up, she was coughing, and the vet didn't seem concerned about it at all. It's now Saturday and the problem still persists. Is this a normal reaction to the tube, or is it more serious?
Laser Reflective Mirror If you're in a mirror-room, and turn a laser on and off, why doesn't the light keep on bouncing forever?
Suppose is a 100% reflective room, and the laser source is hidden, so there's nothing but mirrors, in a vacuum. Since the photons aren't getting absorbed, why wouldn't the laser just continue going forever?
I realize it's an assumption but I'm leaning for the skeptic side. Don't hypotheses start with reasonable assumptions? I would do those experiment at home except I can't afford a particle accelerator at the moment... Thanks for your answers... It's all very interesting.
basic principles of wave propigation. a body in motion tends to stay in motion. if what you're saying is the vacuum is deviod of all matter, including subatomic particles, the wave would continue forever, with one exception. if the beam reflecting around the room collided with itself (say it caught itself in a corner), it would cause sufficient refraction to scatter the beam eventually. photons expend no energy to travel, so the room would stay lit up forever. and man, that would have to be some badass 100% reflective material! ;->
Description Mirror Reflective Screen Protector for your privacy - no one beside you can view your screenJapanese High-Quality Material, 99% Transparency, No BubblesAgainst scratching, scraping & abrasion Removable without leaving residuary mark Resistance to erosion & fingerprintAnti-Reflective, Non-corrosiveCompatible with model: NOKIA N80Total Weight: 13gPackage Includes 1 x screen protector 1 x cloth 
Description Mirror Reflective Screen Protector for your privacy - no one beside you can view your screenJapanese High-Quality Material, 99% Transparency, No BubblesAgainst scratching, scraping & abrasion Removable without leaving residuary mark Resistance to erosion & fingerprintAnti-Reflective, Non-corrosiveCompatible with model: Motorola L7Total Weight: 13gPackage Includes 1 x screen protector 1 x cloth 
The Emergency Rescue Mirror is both a day and night signal mirror that has a special two-sided reflective surface. The silver mirror side is used as a daytime signal mirror and the opposite side is a specially enhanced red mirror for night.Red side is optically designed to reflect light sources at night, to better attract rescue teamsMoving a flashlight side-to-side across the red surface simulates a flashing beacon or ultra-bright flare seen up to 3 miles awayIncludes a lanyard and secure protective pouchSalt and corrosion resistantMeasures: 3.25 inches long x 2.25 inches wide Weighs: 1 ounce
DescriptionMirror Reflective Screen Protector for your privacy - no one beside you can view your screenJapanese High-Quality Material, 99% Transparency, No BubblesAgainst scratching, scraping & abrasionRemovable without leaving residuary markResistance to erosion & fingerprintAnti-Reflective, Non-corrosiveCompatible with model: Motorola V3Total Weight: 13gPackage Includes 1 x outside screen protector1 x inside screen protector1 x cloth
Feature: Act as a mirror use for makeup!99% transparencyNo bubbles & WashableAnti-glareNON-StreakingEasy DIYProtect screen from scratching and dirtNon-corrosive, silicon base adhesion removable, easy to be replacedCompatible with NOKIA N80A piece of cloth available for cleaning screenWeight: 14gMobile phone NOT INCLUDED!!! 
Feature: Act as a mirror use for makeup!99% transparencyNo bubbles & WashableAnti-glareNON-StreakingEasy DIYProtect screen from scratching and dirtNon-corrosive, silicon base adhesion removable, easy to be replacedCompatible with O2 ATOMA piece of cloth available for cleaning screenWeight: 14gMOBILE PHONE not included!!! 
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KHET education activity. Learn how light reflects from a mirror using KHET: the laser game
Laser Cutting: The Fundamentals
When we think of lasers, we may conjure up something seen in the movies. Lasers, however, can be found in real-world industry, making slicing and transforming objects much easier in industry. In laser material processing, a laser will strike a target and alterations to that object will occur, such as through absorption of photons, which are particles of light emitted from the laser. These particles will be changed into heat energy.
How Lasers Actually Work
Lasers are the devices that control how highly stimulated atoms emit photons to create a stream of light. There are only three things that can occur when a laser connects with a material. The laser light stream will either be reflected, sent, or it will be absorbed into the object. Sometimes two or three of these occurrences, such as transmission and absorption, may happen at the same time. The beam will be a certain wavelength and a certain color as well as tight and concentrated, not like beams of light normally found in everyday life. If the majority of the beam is absorbed into an object, which is most often the case in laser material processing, the main traits that have to be taken into consideration are the average strength the laser light has, its intensity on the object it hits, and its wavelength. Intensity on a basic level is the brightness of the laser beam. The wavelength is the sequence of waves the photons create. Think of a moving water wave, the photons are fluctuating in the same type of wave. The average power of a laser beam is measured in watts (W). Lasers all have an active medium that absorbs energy. The medium can be composed of either a solid crystal-like material, fluid, gas (such as in a CO2 laser), or a diode, and holds the atoms absorbing the energy. A laser also has to have a method to make the atoms become excited. This might be a light source, for example.
The optical resonator is a set of mirrors in the laser system. One of the abilities of a laser is to energize the atoms to get them in an excited state. This is done by pumping up what is referred to as a lasing medium inside the laser. At each extreme of the lasing medium is a mirror. Photons reflect off of both of the mirrors and energize other electrons to discharge even more photons. The mirror at one end lets some light through, which is the laser beam. Getting the atoms excited takes getting their matching electrons at a high level of energy. The energized electrons that initially soaked in energy to get excited can now emit energy as light energy, or a stream of photons.
Lasers and Different Classifications
Lasers are rated according to the traits of average power, wavelength, and intensity. This implies they are either solid-state, fluid, gaseous, or semi conductor lasers. Solid-state are lasers with material that is optically clear and the engaged medium is solid. Fluid, or dye lasers have a environment that is liquid and they can work with pulsing or continuous wavelengths. Gas of gas. Examples of gas lasers are CO2 lasers and neon signs seen in shop displays. And the fourth group is semi conductor or diode lasers that are the most common type of laser.
Laser Cutting
Using CO2 lasers as an example, carbon dioxide atoms in gaseous form become excited at a low pressure between two mirrors. One of the mirrors allows a little bit of the light stream escape. They produce a huge amount of heat. The light output is at the end of the infrared spectrum. Having a beam of high quality is important, especially in cutting. Lasers cut by using the light beam the laser makes. The beam starts by melting what is in front of it or oftentimes through vaporization. Cutting occurs when the beam has cut through the object. There are various types of lasers designed to slice various types of materials. CO2 lasers have high capacities for absorption, and are commonly used in the cutting of plastics, wood, stainless steel, carbon steel, aluminum, and other metals such as titanium. CO2 lasers have other materials in them besides carbon dioxide; they have a mixture of gases such as helium (He) and nitrogen (N2). Nitrogen will slice up to ½ inch thick stainless steel in addition to aluminum. Oxygen will cut carbon steel. Laser cutting advantages include no wear and tear on machinery, are faster than using other methods of cutting, and can cut through thicker materials.
Lasers have uses ranging from communications to uses in the field of medicine. They have revolutionized surgery and cutting in industry. It is interesting to see what will happen in the future with laser cutting abilities.
About the Author
Marc Anderes is the VP of Operations of Maloya Laser which specializes in Metal Manufacturing and Laser Cutting with advanced laser technologies, for aerospace, scientific, transportation, medical and machinery requirements.
Zener Diode Voltage Divider could you help me please?
MM74HC4046 Help please?
hi friends..
i am trying to study a MM74HC4046 and had a few doubts.
does it require any source frequency or it can itself provide pulses.
can the vco out and comparator in be directly connected or we need a frequency divider. if i want a frequency of 3.5 MHz can i directly connect the two pins if not which ic shall i use?
can we use zener diodes to regulate the voltage since i would be powering it from 12 v and ic needs just 4.5 volts in normal use?
if i am trying to use thes circuit for my desulfator can zener diode still be used?
pls donot give me links or give forum links. if you know personally then only tell me
1. it contains a VCO, voltage controlled oscillator which is compared to the unknown via one of three phase detectors. The output of the phase detector is integrated and drives the VCO.
look at the data sheet, it has a connection block diagram.
2. yes. Max frequency of the VCO is at least 4.5MHz.
3. It will operate with Vcc between 2v and 6v, although it works better closer to 6 volts. I'd use a 5 volt 3 terminal voltage regulator such as a LM78L05.
4. I have no idea what a desulfator is, and what it has to do with the zener diode.
Current sources and voltage references provide fixed, well-regulated levels of current or voltage within a circuit. These are two of the most important building blocks of analog circuits, and are typically used in creating most analog IC designs. Part 1 shows the reader how current sources are created, how they can be optimized, and how they can be utilized by the OEM circuit designer. The book serves as a must-have reference for the successful development of precision circuit applications. It shows practical examples using either BJTs, FETs, precision op amps, or even matched CMOS arrays being used to create highly accurate current source designs, ranging from nanoAmps to Amps. In each chapter the most important characteristics of the particular semiconductor type being studied are carefully reviewed. This not only serves as a helpful refresher for experienced engineers, but also as a good foundation for all EE student coursework, and includes device models and relevant equations.Part 2 focuses on semiconductor voltage references, from their design to their various practical enhancements. It ranges from the simple Zener diode to today s most advanced topologies, including Analog Devices XFET? and Intersil s FGA"! (invented while this book was being written). Over 300 applications and circuit diagrams are shown throughout this easy-to-read, practical reference book.* Discusses how to design low-noise, precision current sources using matched transistor pairs.* Explains the design of high power current sources with power MOSFETs* Gives proven techniques to reduce drift and improve accuracy in voltage references.
2 in 1 LAN Tester and Multimeter with Voltage, Current, Resistance, Continuity, and Diode Tester Tests Pin Configuration for 10 Base-T, 10 Base-2, RJ45/RJ11, 356A, TIA-569A/568B and Token Ring Cable Remotely Test Cables Up to 330 Yards Away Test Ground Wire Measure DC/AC Voltage, DC/AC Current, Resistance, Continuity, and Diode DC Voltage: Max Range 600 V, Accuracy +/- 0.5% AC Voltage: Max Range 600 V, Accuracy +/- 1.2% DC Current: Max Range 200 mA, Accuracy +/- 1.2% AC Current: Max Range 200 mA, Accuracy +/- 2.0% Resistance: Max Range 20 MO, Accuracy +/- 0.8% Continuity Test: Beeps If Less Than 100 O Accessories Included: Test Leads, LANtest Remote Terminator, 9V Battery, Carrying Case Dimensions: 6.38" H x 2.93" W x 1.73" D Weight: 10.86 oz.
Diode 28 Under cabinet Light LED lighting is the newest advancement in under cabinet lighting technology. LED lights do not use filaments, making them very reliable with a long life span (50,000+ hours). Uses only 5W of power and generates very little heat. Light output is equivalent to one 13W T5 fluorescent or three 20W line voltage Xenon lamps. No remote power supply needed 28 individual LED s provide low glare on counter surface 300 Lumens Three position illuminated push button switch for full or half light output Extended fixture width allows a wide, even light distribution Slender 3/4 inch profile ABS molded housing and diffuser Plugs directly into 120V outlet, cord included Can be end-to-end connected with direct connector, included Connect up to 20 fixtures Use 12 inch modular connecting cord, included, for multi-fixture daisy-chain connection or use to plug into hardwire box Hardwire connection through optional hardwire box Screw-in or double-sided adhesive mounting 28 5W TOTAL Requires model number XNHB kit for hardwire installations.
Contemporary / Modern Diode 28 LED Under Cabinet LightThe Diode28 LED undercabinet light is the latest advancement in undercabinet lighting. LEDs have a long life span 50,000+ hours, use only 5W of power and produce very little heat. Light output is equivalent to one 13W T5 lamp or 3 20W line voltage Halogen lamps. No remote power supply needed. This unit is wired with a UL listed electronic circuit board containing 28 individual 1/4 watt LEDs for 120V/60 Hz AC operation. It has a three position illuminated push button switch for full or half light output. Extended fixture width allows for wide, even light distribution. The included 5 foot cord plugs directly into 120V outlet-cord included. It can be connected end to end with the included direct connector. Connect up to 20 fixtures with 12" modular cord-included. Hardwire connection can be done through optional hardwire box. When you consider lighting, be bold, be original, be environmentally smart. Choose American Fluorescent. Offering the perfect union of lighting beauty and smart design, American Fluorescent has re-defined energy-efficient lighting.Features:28 LED Undercabinet FixtureSlender 3/4" ProfileABS Molded Housing and DiffuserScrew-In or Double-Sided Adhesive Tape MountingThree Position Illuminated SwitchConnect up to 20 FixturescULus Listed for Dry LocationsSpecifications:Includes (28) 1/4 Watt LED DiodesHeight: .75"Length: 9.5"Width: 6.25"
Manufacturer's 2 year guarantee. EAN/MPN/UPC/ISBN: 5055257515161. Mains operated. Approved for home use. Includes laser hair unit, instructions, step-by-step DVD. Clinically proven. Safe for use on facial hair. Chemical free. Not suitable for use on white or grey hair, Afro- Caribbean hair or very dark skin. Suitable for targeting problem hairs in sensitive areas. Three treatment modes; one treats individual hairs the other two modes scan larger areas. By Rio.
Diode Thermometers What Temperature Should My stenodactylus stenodactylus gecko's (dwarf geckos) be kept at?
I bought some stenodactylus stenodactylus gecko's (dwarf geckos) yesterday, i have a heatmat and all that, but i dont know how hot the heatmat should be, i have an electric a thermometer diode in the tank, and that is reading 30oC right now on the heatmat. The Gecko's are from N. Africa, what temperature should the heatmat be at??
Thanks
Karl
Awesome, Thanks Bonny
Between 80-90f is the best for a dwarf gecko. This will enable enough humidity and heat to help the gecko digest it's food and be warm enough to be active.
All ATI Thermometers are manufactured under the same stringent FDA regulations that govern procedures, tests, and quality standards for medical products. They are accurate within plus or minus one degree.
All ATI Thermometers are manufactured under the same stringent FDA regulations that govern procedures, tests, and quality standards for medical products. They are accurate within plus or minus one degree.
Features of the Clinical NexTemp Thermometers: NexTemp® thermometers are less expensive than any other type of thermometer. They require no special storage conditions, batteries, covers or recalibration processes. NexTemp thermometers are easier to use and read compared to predecessor dot-matrix thermometers. NexTemp thermometers replace dangerous glass/mercury, digital electronic and tympanic thermometers. NexTemp thermometers and packaging contain no latex and are non-toxic. They conform to ASTM E1299-96 safety requirements. NexTemp color-change thermometers have been proven under strict clinical conditions and meet stringent ASTM accuracy requirements.
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Simple PIC Thermometer with a diode as sensor
Realizing computerized incubator with the aid of real-time technology
Realizing computerized incubator with the aid of real-time technology
1James Agajo, 2 A Sylvester Ezewele 3Awolo C. I.
Department of Electrical/Electronics
Federal Polytechnic, Auchi
Edo State ,Nigeria
Email: agajojul@yahoo.com
Phone: +2348053312732
Abstract:- Realizing computerized incubator with the aid of real-time technology , describe the design and implementation of an intelligent temperature controller based on fuzzy logic technology, the problem of precision in temperature control and monitoring was analyzed., microcontroller was programmed with the aid of EPROM programmer in realizing its automation.
Computerized incubator is an apparatus in which environmental conditions, such as temperature and humidity, can be controlled, often used for growing bacterial cultures, hatching eggs artificially, or providing suitable conditions for a chemical or biological reaction with the aid of real-time integrated system. They are special warm enclosure for keeping fertilized eggs to ensure satisfactory development of embryos inside them into normal birds.
Incubation of fowl eggs usually lasts for 21 days. The stage, eggs incubation is the most delicate stage in poultry husbandry because the proper care of eggs at this stage of developments has a decisive influence on the number of birds to be hatched and health of the hatched birds.
Fundamental elements of incubation are: the provision of heat, humidity, ventilation and turning of the eggs. The efficient combination of these factors determines the level of biological and physiological development and mortality of the embryo.
1.1 Incubating Conditions
Poor results are most commonly produced with improper control of temperature and humidity. Improper control means that the temperature or humidity is too high or too low for a sufficient length of time that it interferes with the normal growth and development of the embryo. Poor results also occur from improper ventilation, egg turning and sanitation of the machines or eggs. Obtain the best hatch by keeping the temperature at 100 degrees F. throughout the entire incubation period when using a forced-air incubator. Minor fluctuations (less than ½ degree) above or below 100 degrees are tolerated, but do not let the temperatures vary more than a total of 1 degree. Prolonged periods of high or low temperatures will alter hatching success. High temperatures are especially serious. A forced-air incubator that is too warm tends to produce early hatches. One that runs consistently cooler tends to produce late hatches. In both cases the total chicks hatched will be reduced.
Maintain a still-air incubator at 102 degrees F. to compensate for the temperature layering within the incubator. Obtain the proper temperature reading by elevating the bulb of the thermometer to the same height as the top of the eggs when the eggs are laying horizontal. If the eggs are positioned in a vertical position, elevate the thermometer bulb to a point about ¼- to ½-inch below the top of the egg. The temperature is measured at the level where the embryos develop (at the top of the egg). Do not allow the thermometer's bulb to touch the eggs or incubator. Incorrect readings will result.
2.0 Components and Appliances Used For the Design and Their Characteristics
1) IC 8952 (Microcontroller)
2) Active devices
Transistors (BC 337- NPN, BC 557-PNP)
Crystal oscillators
Diodes
3) Passive Devices
Capacitor
Resistor
4) The micro switch
5) The Transformer
6) The regulator 7805
7) The comparator (LM324)
The seven segment display
9) The relay
10) The Temperature Sensor (LM 35)
11) Electric bulb (100W)
12) Fan
These components are briefly discussed below:
2.1 8952 (Electrically Erasable programmable Read Only Memory)
IC 8951 is a microprocessor, which is a mini-computer –on-a-chip
The 8952 microcontroller is in practice a complete computer. It possesses the following characteristics:
4KB of Read-Only Memory (ROM)
Four 8-bit I/O ports
256 x 8 of Random Access Memory
A Programmable Serial UART port
Six Interrupt Sources
External memory interface
Standard 40-pin package
Two 16-bit timer/ counters
Though the frequency of a crystal oscillator depends on how it is cut. That is, the frequency is determined by the manufacturers, but a careful analysis of the parameters that make up the frequency is as shown below.
Assuming the following parameters;
L = 0.33 H, Cs = 3.0 x 10-3PF, CP = 1.1 PF, R = 10K
The series resonant frequency:
FS = 1/2p (1/LC) 1/2………………………………………..2.1
FS = 1/2p (1012 )1/2
0.000099
= 15995673.6 Hz
... The series resonant frequency, FS, is approximately 16MHz.
To calculate the percentage by which the parallel-resonant frequency exceeds the series- resonant frequency, we have;
Fp = (1+CS)1/2 ……………………………………..2.2
FS CP
= (1 + 0.00030)1/2
1.1
= (1 + 0.000273)1/2
= 1.36
Therefore, FP exceeds FS by 33%
3.0 LM 35 TEMPERATURE SENSOR
The temperature sensor used in this project is the LM35. The LM35 measures temperature and gives an output voltage that is proportional to the Celsius temperature.
The LM35 has a low output impedance, linear output and precise inherent calibration that make interfacing to readout or control circuit especially easy.
The supply voltage (Vcc) is usually held at 5V. It draws only 60mA from its supply and hence possess a low self-heating capability. The sensor self-heating causes less than 0.1oC temperature rise in still air.
In the circuit, the Vout pin is connected to the Vin(+) pin of the ADC0804 while the Vcc is connected to a 5V supply and the GND pin grounded.
The sensor has a sensitivity of 10mV/oC. The conversion factor is 100oC/V.
The general equation used to convert output voltage to temperature is:
Temperature(oC) = Vout C 100oC/V.
So if Vout = 0.5V, then temperature = 0.5 x 100 = 50oC
Again, if the temperature controller is set to maintain the temperature below 30oC, then the maximum output voltage that will trip the relay is
Vout = 30oC/100 = 0.3V
The LM35 in measures temperature and gives an output voltage that is proportional to the Celsius temperature.
The scale factor is 0.0IV/OC. It does not require any external calibration or trimming and maintains an accuracy of +/- 0.8oc over a range of Ooc to + 100oc.
It also draws only 60 micro amps from its supply and possesses a low self-heating capability. The sensor self-heating causes less than OO/OC temperature rise in still on.
Typical voltage value of the LM35 is 5V. The sensor usually has a sensitivity of 10m V/oC.
The LM35 was actually built from the same resistance characteristics of devices such as the NTC Thermistor, which is a function of temperature. They usually have a low thermal are quickly reflected in a varying resistance as the mass.
For a thermistor, an expression for the resistance at any temperature is given by
(1) R = RO* exp (Beta (1/T – 1/T o))
Where Beta is a constant force particular thermistor temperature TO and T are usually in degrees Kelvin. Typical values for R-O and T-O are 10.0k ohms and 300.0 degrees k.
Values of Beta are typically in the range of 3000 4000.
T – Kelvin = (T – f – 32.0) / 1.8 + 273
A general expression for temperature (T) as a function of resistance (R) is developed.
(2) /T = 1/Beta X In (B) –1/Beta X In (Ro) + 1/T- 0
Substituting RO = 8870.0, TO = 300.9 and Beta = 3423.
(3) 1/T = 6.292 e-6 *In (R) + 6.6906e-4
The temperature in degree s I may than be calculated using the relation.
I – f = (T – K – 273.0)* 1.8 + 32.6
However, voltages at nodes, given x and y could also be calculated using the following relations.
(i) V – x = 20.Oe3/(20.0e3 + R – Therm)* V – bridge
An ADC is an electronic device that converts continuous signals to discrete digital numbers. The reverse operation is done by a DAC. The digital output may be using different coding schemes such as binary and two’s compliment binary.
Most ADC’s are of a type known as linear which means that the range of input values that map to each output value has a linear relationship with the output value.
The ADC used is an IC, ADC 0804.
The analogue voltage in figure 2a is applied to pin 6 and the result is available at P0.0 through 0.7 .Pin 1 and 2 (chip select and read) are connected to ground so that the chip is enabled. Pin 7 is also connected to ground.
The ADC 0804 includes an internal oscillator, which requires an internal capacitor and resistor to operate.
A 150Pf capacitor is connected from Pin A (Clock IN) to ground and the 10k ohm resistor from Pin 4 to Pin 19. (Clock R).
If the input range of ADC is O-5V. Then Vref is set at 0.5, Vin maximum = 2.5V Because ADC 0804 is 8bit, then
resolution = 255/5 = 0.02V
This means the ADC will respond each 0.02V increasing. When conversion process is complete, P3 (interrupt) will go how and this signal is used to convert ADC again.
Thus, an ADC with a resolution of 8bits can encode an analogue input to one in 256 different levels, since 28 = 256.
Resolution can be expressed electrically and expressed in bits. The voltage resolution of an ADC is equal to its overall voltage measurement intervals as in the formula.
Q = EFSR/2m-1
Q = resolution in volts
EFSR = full scale voltage range
M = resolution in bits
Q = 5/2m – 1 = 5/ 255
Q = 0.02V
RESOLUTION
The resolution of the converter indicated the number of discrete values it can produce over a range of analog values.
The values are usually stored electrically in binary form, so the resolution is usually expressed in bits.[1]
SAMPLING RATE
The analog signal is continuous in time and it is necessary to convert this to a flow of digital values. It is
Therefore required to define the rate at which the new digital values are sampled from the analog signal.
The rate of new values is called the sampling rate or sampling frequency of the converter.
ERRORS IN ADC
An ADC has several sources of error Quantization error and non-linearity in intrinsic to any A to D conversion.
Quantization error is due to the finite resolution of the ADC and is on unavailable imperfection in all types of ADC.
STEPS TAKEN IN ASSEMBLING THE PROGRAM
a) Type the program in notepad.
b) Save it as “tempControl.asm” in drive C:/
Ensure that drive C:/ has the 3 aplications (A51,OHS51 and L51) required to assembly the program
c) Launch the “run” command from the start menu and type the commands
a51.tempcontrol.asm
l51.tempcontrol.obj
ohs51.tempcontrol.obj
and then click OK,You cannot actually make the difference between the two steps, as the process is completely automated and indivisible. In case of syntax error in program code, program will not be compiled and HEX file will not be generated. Errors need to be corrected in the original .pbas file and then the source file may be compiled again. The best approach is to write and test small, logical parts of the program to make debugging easier.
The PM-51 Macro Assembler was used for this project. The term PM-51 belongs to an entire family of single-chip microcomputers, all of which have the same processor design. They use the same instruction set, but differ slightly in
Memory mapped special function registers and on-chip ROM and RAM. The assembler is a software tool- a program-designed to simply the task of writing computer programs. It performs the clerical task of translating symbolic code into executable object code. This object code may then be programmed into one of the PM-51 processor to which the 8051 belongs.
4.0 DEVELOPMENT OF THE PROGRAM
(i) Program Entry and Edit
After the design is completed, the source code for each module is entered into file using a text editor. When errors are detected in the development process, text editor may be used to make correction in the source code.
(ii) Assembling the Program:
The microcontroller cannot understand programs entered in assembly language. The process of converting assembly language into a suitable format is known as assembling the program. This is done using a program called assembler (ASM51) which translates the source code into object code.[1]
5.0 Tests and Result
The test was done by powering the incubator. When powered it displayed “set temperature”. The required temperature was entered using the increment button. Then the incubator attained the required temperature.
Also the work was tested and found to meet our specified requirement with efficiency of 70%.
No of fertile eggs used are 50
No of chicks hatched are 35
About the Author
James Agajo is into a P.H.D programme in digital signal processing related area, he has a Master Degree in Electronics and telecommunication Engineering and also possesses a Bachelor degree in Electronics and Computer Engineering from the Federal University of Technology Minna Nigeria. To his record, he has carried out researches in various areas as it concern telecommunication with particular emphasis on wirless communication network. His interest is in intelligent system development with a high flare for Engineering and Scientific research.He has Designed and implemented the most resent computer controlled robotic arm with a working grip mechanism 2006 which was aired on a national television , he has carried out work on using blue tooth technology to communicate with microcontroller. Has also worked on thumb print technology to develop high tech security systems with many more He is presently on secondment with UNESCO TVE as a supervisor and a resource person. James is presently registered with the Nigeria Society of Engineers.
Thanks for your answers... It's all very interesting.
The seven segment display