Proximity sensors working on an induction principle are able to detect ferrous and non-ferrous metals very reliably.
For those of you, who already work in this field, there´s everything clear for you probably and you know well, that induction sensors are literally one of the keystones for an industrial automation. For all of you, who´re not familiar with these important components yet, we bring this short description.
Induction sensors use the fact, that metal parts placed near an oscillator coil are able to change condition in a given oscillating circuit. Such a change (stopping of oscillations) can be reliably evaluated and to gain a confirmation about a presence of a metal subject in the sensor´s range. Induction sensors typically work on a frequency of hundreds of Hz up to a few kHz.The bigger the size of a coil (and also a sensor), usually the higher is the resulting sensitivity of a sensor (sensing range). But at the same time a bigger sensor usually works on a lower frequency, that´s why even a maximum sensing frequency is lower. From this reason it´s usually better to use a smaller type to detect fast moving objects.
Omron, as a top class producer of industrial sensors has in its portfolio a lot of series of induction proximity sensors, in numerous versions. A typical representative of well-known widely used sensors is the Omron E2A series. E2A has increased detection range and it´s encapsulated in a body from a nickel pated brass (M12-M30) or a stainless steel (M8). A lot of versions and diameters can be found here (M8/M12/M18/M30), versions with connectors or wire leads and also shielded and unshielded versions.
„Shielded” means, that a metal sensor body reaches up to the front (sensing) portion of a sensor. In case of non-shielded versions the metal package is shorter, i.e. the plastic part seems to stand out of the sensor body. The result is that a non-shielded version is more sensitive even to sides (x), what can be advantageous in some applications. On the other hand, shielded versions provide possibility of a very close assembly of sensors next to each other. Series E2A has a high resistance to dust and water (IP67/ IP69k), shocks, vibrations, heat as well as electromagnetic interference.
E2A series is primarily intended for ferrous metals, but with a smaller sensitivity it´s also usable for non-ferrous metals. However in the Omron offer can be found series specially intended for aluminium and other non-ferrous metals and even types which are non-sensitive to ferrous metals.
A typical output of an induction sensor is a transistor (open collector) – PNP or NPN with protection components (diode + transil). Output transistor can be used to connect to an intelligent control unit, or for direct switching of circuits, or switching of relays.
Overview of Omron offer and hints for usage can be found in the Omron induction sensors application guide. Detailed description of the E2A brings the Omron E2A datasheet. Answers to many questions can be found on the Omron proximity sensors FAQs webpage.
Induction sensors don’t need a touch, they’re satisfied by proximity - [Link]
The most legendary PIN-diode which is also used as a nuclear radiation detector is the BPW34. It is available from several semiconductor manufacturers in different variants and was originally designed for visible and invisible wavelength up to the IR wavelength region. Since such a diode is sensitive to light the use as a nuclear radiation detector requires proper shielded against light. The cost of a BW34 diode is generally below 1 Euro.
Do-it-yourself PIN-diode counter - [Link]
Freescale Semiconductor today introduced the FXTH87 tire pressure monitoring system (TPMS) family, which is the smallest integrated package TPMS solution available at an extremely light weight of 0.3 grams. The FXTH87 family is 50 percent smaller than competing products, helping designers reduce overall bill of materials costs. Freescale’s newest TPMS system-in-package solution provides low power consumption combined with the highest level of functional integration in one package, featuring a dual-axis accelerometer architecture, pressure and temperature sensor, integrated MCU, RF transmitter and low frequency receiver.
Freescale introduces world’s smallest integrated tire pressure monitoring system - [Link]
An app note on Gamma-photon radiation detector (PDF) by Maxim:
A PIN photodiode, four low-noise op amps and a comparator are used to detect individual photons of gamma radiation. The schematic, design considerations and component selection are discussed.
Gamma-photon radiation detector - [Link]
by Jordan Dimitrov @ edn.com:
While most carbon dioxide sensors use IR technology, electrochemical sensors are a serious competitor because of their high sensitivity, wide measurement range, and low price. As a rule, electrochemical sensors connect to a microcontroller through a buffer amplifier with an extremely low bias current (<1pA). The micro is needed to linearize the logarithmic response of the sensor. A good example of this approach is the SEN-000007 module from Sandbox Electronics, which uses an MG-811 CO2 sensor from Hanwei Electronics. Reference 1 reveals the circuits and the code, but does not specify accuracy.
Antilog converter linearizes carbon dioxide sensor - [Link]
Ioannis Kedros writes:
It’s been a long time since I’ve post a new hobby project of mine! I decided that is time to upload a new one! Like my Sensor Stick module this project will be about sensors as well.
You can find multiple modules out there with various sensing ICs that almost all of them look exactly the same! They are ugly and without properly markings on their surface.
For example, some of those don’t have the input voltage range on the PCB or the pin out names or even the sensor address (in the case of a digital I2C sensors for example). In order to find that info, you have to download files, unzip them, look the schematics of the module then the datasheet of the sensor etc. A time consuming method especially for a quick and dirty prototype!
embeddedday.com – Sensor Modules - [Link]
Davide Gironi writes:
DS18B20 is a programmable resolution 1-wire digital thermometer.
It has an operating temperature range of -55°C to +125°C and is accurate to ±0.5°C over the range of -10°C to +85°C.
This library is an AVR implementation to retrive temperature from DS18B20.
Built using the reference document: “Using DS18B20 digital temperature sensor on AVR microcontrollers” by Gerard Marull Paretas, 2007.
A DS18B20 1-wire digital thermometer AVR ATmega library - [Link]
Cambridge Sensors Ltd have announced the appointment of the ASE group to assemble and test there latest tiny (currently the world’s smallest) gas sensor. The 2.0mm x 3.0mm cavity DFN package developed together with ASE enables the integration of gas sensors into devices such as smartphones, tablets and wearable devices where it has previously not been physically possible.
The CCS800 product family of ultra-low power miniature gas sensors can be used for detecting Ethanol (Alcohol) and hazardous gases such as Carbon Monoxide (CO) and a wide range of Volatile Organic Compounds (VOCs) including Formaldehyde. According to Fuyu Shih the vice president of ASE Europe: “The Global emergence of sophisticated electronics geared towards improving lifestyle and efficiency is fuelling the sensor market, making it one of the fastest growing areas of innovation within the semiconductor industry”.
Smartphone Nose - [Link]
Project is based on Holteks IC HT7610A, which is a CMOS LSI chip designed for use in automatic PIR lamp, flash or buzzer control. It can operate in 3-wire configuration for relay applications. In our project we have used relay instead of Traic to connect any kind of load in output, HT7610B IC is suitable for traic and HT7610A for Relay application. The chip is equipped with operational amplifiers, a comparator, timer, a zero crossing detector, control circuit, a voltage regulator, a system oscillator, and an output timing oscillator.
Its PIR sensor detects infrared power variations induced by the motion of a human body and transforms it to a voltage variation. If the PIR output voltage variation conforms to the criteria (refer to the functional description), the lamp is turned on with an adjustable duration. The circuit doesnt required step down transformer and can work directly by applying 110V AC or 220V AC (Capacitor C7 needs to change for 220V AC (0.33uF/275V) and 110V AC (0.68uF/275V)
PIR Sensor - [Link]