In the broadest definition, a sensor is a device, module, machine, or subsystem whose purpose is to detect events or changes in its environment and send the information to other electronics, frequently a computer processor. A sensor is always used with other electronics.
Sensors are used in everyday objects such as touch-sensitive elevator buttons (tactile sensor) and lamps which dim or brighten by touching the base, besides innumerable applications of which most people are never aware. With advances in micromachinery and easy-to-use microcontroller platforms, the uses of sensors have expanded beyond the traditional fields of temperature, pressure or flow measurement, for example into MARG sensors. Moreover, analog sensors such as potentiometers and force-sensing resistors are still widely used. Applications include manufacturing and machinery, airplanes and aerospace, cars, medicine, robotics and many other aspects of our day-to-day life. There are a wide range of other sensors, measuring chemical & physical properties of materials. A few examples include optical sensors for Refractive index measurement, vibrational sensors for fluid viscosity measurement and electro-chemical sensor for monitoring pH of fluids.
A sensor's sensitivity indicates how much the sensor's output changes when the input quantity being measured changes. For instance, if the mercury in a thermometer moves 1 cm when the temperature changes by 1 °C, the sensitivity is 1 cm/°C (it is basically the slope dy/dx assuming a linear characteristic). Some sensors can also affect what they measure; for instance, a room temperature thermometer inserted into a hot cup of liquid cools the liquid while the liquid heats the thermometer. Sensors are usually designed to have a small effect on what is measured; making the sensor smaller often improves this and may introduce other advantages.Technological progress allows more and more sensors to be manufactured on a microscopic scale as microsensors using MEMS technology. In most cases, a microsensor reaches a significantly faster measurement time and higher sensitivity compared with macroscopic approaches. Due to the increasing demand for rapid, affordable and reliable information in today's world, disposable sensors—low-cost and easy‐to‐use devices for short‐term monitoring or single‐shot measurements—have recently gained growing importance. Using this class of sensors, critical analytical information can be obtained by anyone, anywhere and at any time, without the need for recalibration and worrying about contamination.
Anyone has got an idea about a sound sensor ( that is really sensitive !) , i.e., can sense the sound levels of 20-25 db to convert them to electrical signals...or atleast how to make such a sensitive sensor...
Almost all the cars now use an Electronic Throttle Body for Controlling airflow into the engine. In order to make the system Fail-safe, manufacturers use two Potentiometers for the throttle position sensor feedback.
My doubt is regarding the method used for tapping output from both the...
Hi!
I am using this hall sensor http://docs-europe.electrocomponents.com/webdocs/0d88/0900766b80d88153.pdf
i got 2 problems:
1. When i vary the magnetic field, the hall sensor is acting like digital, i mean, it showing either high value or low value... Its not varying linearly as the distance...
I want to build my own circuit sensor.
I opened the digital scale.I built the circuit on breadboard.The sensor is silverish color in the picture.
I have completed my circuit on breadboard but don't know how will this sensor work.
Can someone tell me what is the mechanism of this specific...
I understand the role of an image sensor is to convert incoming light into electrical charge (by splitting the light into RGB values and then measuring the intensities of each), but how does this occur?
I know the answer is very basic (the sort of sensors I'm talking about are CCDs and CMOS)...
Hello,
I’m currently working on a project in which I need to know the weight distribution in the four tires of a car at all times. I was thinking to install strain gauges somewhere in the chassis, or displacement sensors by the suspension. However I don’t feel these methods will give me...
I helped my colleagues simulate inductance of vr crank sensor in Maxwell but my simulation result is quite different compared to the test one.
Our sensor is quite simple, just a piece of permenant magnet, a piece of flux concentrator made of normal steel, and one copper coil hooked outside of...
Output resistance problem
Homework Statement
Hi,
I am not getting the answers right, and I think I misunderstand the logic behind this circuit.
http://imageshack.us/photo/my-images/577/screenshotfvm.png/
Homework Equations
I know that the equation of Vin is Vin=(VsRin)/(Rs+Rin)
and...
I'm working on a sensor signal conditioning circuit. The sensor output has a 2.5V DC bias with a peak-to-peak voltage swing of about 50mV. The signal output is put through a demodulator and then filter (LPF) to obtain a DC voltage proportional to the out of the sensor. The problem is I need to...
Hey guys -
I've been looking to find an oxygen sensor that fits certain criteria. I've been looking through oxygen sensors on Google and I can't really figure out what kinds of inexpensive oxygen sensors are available that aren't meant to go inside car exhausts. I would really appreciate it if...
I need to read out the temperature of ZrO2 devices which rotate along their axis between 10-100 kHz by using dry compressed air.
The external diameters of each device are: 1mm, 3mm or 4mm, and they rotate inside a special stator
The actual rotation speed is read by an optical fiber...
Hi, I'm working on an idea and i need some guidance
say i have a wire loop of a single wire (not solenoid) the area of the loop is about 1-2 cm^2
now say i change the area of the loop slightly by about 0.1%-0.01%
could i measure with today's electronics this slight change of L
thanks in...
Hi guys,
I'm trying to design a brushless motor for an EV with temperature sensing for both the copper coils in the stator and the permanent magnets in the rotor, but I'm not sure how to add a temperature sensor on the neodymium magnets in the rotor. Wouldn't the high levels of varying...
Hi There, I'm looking for ideas on finding the position of objects (such as a hand or foot) placed in a tank. Without using a camera soultion, I think the use of something like a minature laser range finder or IR proximity sensor. My problem is that I need to find distances between 5cm (min...
Hello everybody,
I am trying to figure out if a heated enclosures will effect my temperature readings from a temperature probe. As shown in the picture below, the arrow in the middle shows an enclosure 9"x7"x8" that has a 30 watt heater inside and a battery backup system 27"x 22" x 18" on the...
So I've been looking at magnetic sensor datasheets and I see the sensitivity is usually listed in units of mV/V/gauss. What does this mean?
Let's say I need to sense changes in a magnetic field that usually ranges from about 10 gauss ( 1 mT ) to about 130 gauss ( 13 mT ). And I need to be able...
I am just confuse about zinc oxide being a gas sensor. What I am implying is that why it can detect gases such as methane and C2H5OH? What are the properties of ZnO as a gas sensor?and what is the physics behind this gas detection?
I've developed a new concept called "Ambient Light Ignoring Infrared Active Distance Sensor". It consists of a transmitter with an infrared LED which uses a traditional LM555 timer to oscillate a frequency of 5kHz and a modified receiver which consists of a common emitter setup, NPN...
hi everybody.
a friend of mine needs to make an ammonia sensor from the mq137 sensor, but we couldn't find a circuit anywhere. can any of you guys help us out? we need it to trigger a relay when a preset threshold is reached. thanks in advance!
Hi ALL,
I'm glad I found this Forum. I'm an engineer, rusty with my math, building a practical prototype sensor that will characterize energy from 8 directions at shallow angle, upon
a solar array.
I need help with expression showing the summation of each of the 9 sensors (with the...
Hi. I've just started working with the MPR121 capacitive sensor (at the moment I'm working with the MPR121 breakout board sold by sparkfun) for an application that involves detecting a toolhead's distance above a work surface. It's not a problem to ground part of the tool head and some initial...
Hi,
I need a little help trying to determine the possibility of incorporating touch and motion sensor technology in material like rubber, plastic or glass. My question is as follows:
Is it possible to incorporate touch and motion sensor technology in material like rubber, plastic or glass...
I have a simple home built pulse sensor that uses light from an LED to measure the opacity of my skin. As my heart beats the opacity of my skin goes up an down in a saw tooth like pattern. The frequency of this wave is my heat beat. The frequency is easy enough to find manually (by counting the...
I'm trying to build a non-contact displacement sensor, sensitive to motion in the micrometer to millimeter range, for a research project. My two best choices are a self-mixing laser interferometer and a capacitive displacement sensor. Has anyone had enough experience with these types of sensors...
Homework Statement
Suggest a sensor with a signal conditioning can be used for measuring each of the following physical variables "heat, electrical current, angular displacement, pressure and heart beats"?
Homework Equations
The Attempt at a Solution
Heat: sensor: thermometer or...
Hi,
I am trying to measure the center deflection of a simply supported beam with a capacitive sensor. The beam's surface that is the sensor's target is originally flat. After applying equal forces on the two edges of the beam, its center curves upwards (away from the capacitive sensor) thus...
I am doing a project, where I am measuring the tension exerted by different guitar strings from different sets for the classical guitar.
I have a Vernier dual force sensor to do it, so the method would be just attaching one end of the guitar string to the Vernier sensor, while the other end...
Hi all,
We're working on a project where we try to calculate the distance traveled by a mobile phone which is thrown in the air (only vertical movement, not horizontal).
We use the accelerometer to get the acceleration in the x-, y-, and z-axis. Now we try to fix the error caused by the...
Andy has elaborated about photo sensors https://www.physicsforums.com/showpost.php?p=3091595&postcount=2. The essential part:
This gives the impression that a lot is wasted. If a "red" photon happens to hit a blue filter, it's lost. So every "pixel" containing two green and a red and a blue...
Hello!
So, pet project. Basically, I'd like to be able to monitor the distance between two moving points, with distances varying from 0-2m or so, with a resolution of at least 5cm or so. (The actual application is to measure the distance between a person's feet while moving, running, jumping...
Homework Statement
A sensor is at rest in a fuel tank , it is at a depth of 0.34m
and the fuel has a specific gravity of 0.7 .
Calculate the pressure experienced by the sensor ?
Homework Equations
I guess Pressure = force/area
The Attempt at a Solution
I considered gravity as...
I was reading this journal on FO-PPR sensor and had a doubt. Couldn't exactly google for an answer as it was unclear.
"Integration of fiber optic-particle plasmon resonance biosensor with microfluidic
chip" by a group of scientists.
I have attached the pdf.
Under the section "Preparation of...
Hi, I am currently designing a stabilisation device for use in water. The general idea is using an inertial motion sensor to detect the orientation and propellors to correct it. I have very little knowledge in this area and was wondering whether I can use a phidget to achieve a wireless feedback...
Homework Statement
I am trying to figure out how this ckt works. But no idea, where to even begin.
see attachment tp.png
Homework Equations
The Attempt at a Solution
Q1 is diode connected. The Vbe temperature dependence is amplified to indicate the temperature. -2mV/ deg C
Gain...
Hi all,
I am trying to connect a Parallax PIR motion sensor to a mini-usb cable.
The PIR sensor has three pins: GND (negative), VCC (positive) and OUT.
The USB cable has four connections: GND, VCC and the DATA (+ and -).
I am able to power up the sensor and see a voltage spike when...
Hi,
I was trying to measure DC link current on a switched mode power supply when I came across a quirk of my circuit. I'm using an LEM HX 03-p SP2 hall effect current transducer to measure current. I couple the output node of my current transducer to ground via a 2KΩ resistor. The device's...
Hello
I'm designing a project and i need a sensor that can detect human motion.I would like to detect the output signal of this sensor by searching it via laptop or mobile phone as if they are searching for a wifi signal.
I would like to know if such sensor is available or should i build a...
I feel really stupid for asking this.. but how does this sensor work? I'm not really good at electronics.
What I mean is, if I have air flow through a pipe, how would I use this, through the small pipe that comes out the top? Or maybe put it inside the tube? Or is this an atmospheric pressure...
Hi.
I have a few questions about sensor specifications and its implementation in a Kalman Filter and simulation of gyroscope/accelerometer output.
Abbreviation used:
d - discrete
c - continuous
Q1:
From book: Aided Navigation - Farrell (you don't need the book to understand the...
Dear PFs
I am facing a problem with finding a good Hall-effect magnetic flux sensor which should be fixed in the top of a probe working in a very intense magnetic field.
The probe must be aligned to a certain degree with respect to the direction of the main field. The requested alignement...
Hi Guys,
I'm currently doing my final year project which my title is to design a remote sensor to monitor home electrical apparatus by using hall effect sensor.
I've build a basic circuit and amplifier to test my hall effect sensor ic ( linear) with a magnet. Everything works fine and now...
Hi friends,
I'm an outsider with a management science background looking for a solution into a technical matter I can't resolve by scouring the net. I am working on an academic project that will allow me to track multiple pressure or force points and have that information transmitted...
I don't know about you people, but I often loose my milk, because it boils and spills out, just when I am not looking at it. :)
Is it possible to alarm when it is just about to boil, by sensing its temperature?
My concern is, is temperature a reliable indicator (impurities, varying degree of...
I am beginning a new project in which I plan on using the distance between my hands as a measurement. Being new to electrical engineering, I am not quite sure of what type of sensor to use to accomplish this. I would the sensor in one hand to only pick up the receiver in the other hand, not just...
Hello, I'm not an electrical engineering student so please bare with me...
anyways if let's say you swallow a pill containing a piezoelectric sensor to measure adsorption of a molecule in the stomach how can you detect the changes in frequency? if there is no "physical" electrical connections...
I'm an old digital guy working on a little analog oscillator project so I'm a bit in over my head. The objective is to detect alloy deviations in samples of aluminum scrap: a very simple go/no-go detector
I've cobbled together an inductive meter design using a dual op-amp sine wave...
Here's the circuit-
It isn't clear to me which part of this circuit makes the voltage divider and also it doesn't show where the voltage output is on the circuit. Can someone tell me those two things please. Also I don't understand why voltage increases as resistance increases in the LDR...