by kinasmith @ instructables.com:
This is a tutorial on building a Compost Temperature monitoring system. It details how to build a web connected wireless sensor network and shows one possible way it could be constructed.
A Medium level of knowledge and skills are required. Basic knowledge of soldering and breadboarding will be very useful. I will assume that you know enough Arduino code to understand what a Function is, how a Library is useful, and why Serial Communication is important. And you will need to know enough electronics to understand what I mean with terms like Voltage, Current, Resistance, etc. A (very) basic knowledge of how radio works would also be useful for understanding the concepts, but not essential for following along. This is not advanced by any means and I will attempt to always reference materials that will cover these concepts in greater detail.
Compost Sensor – [Link]
by Ron Quan:
In some JFET op amps such as the AD743, the input capacitance is in the order of 18 to 20 pF. In comparison, with an LSK489 dual FET, the input capacitance is in the order of 3 pF, which will be suitable for low noise photodiode applications. In this section we will see why it is important to have low equivalent input noise and low input capacitance in a photodiode preamp.
A Guide to using FETS for Sensor Applications – [Link]
by codebender_cc @ instructables.com:
The MQ series of gas sensors use a small heater inside with an electro-chemical sensor. They are sensitive for a range of gasses and are used indoors at room temperature. The output is an analog signal and can be read with an analog input of the Arduino.
The MQ-2 Gas Sensor module is useful for gas leakage detecting in home and industry. It can detect LPG, i-butane, propane, methane ,alcohol, hydrogen and smoke.
Some modules have a built-in variable resistor to adjust the sensitivity of the sensor.
How to use MQ2 Gas Sensor – Arduino Tutorial – [Link]
by dkroeske @ github.com:
A cheap 555 timer chip acting as Schmitt trigger combined with a phototransistor or LDR is taped to the ‘flashing light’ or ‘pulsing magnet’ on the electricity meter. The output of the 555 timer chip is connected to one of the GPIO pins on the Raspberry Pi. A Python script (executing in the background) recording 555 events is calculating actual energy usage [e.g. Watt] every time the 555 is signaling and stores epochs in an SQLite3 database. From this, another Python script (executed from e.g. cron) generates all kinds of energy usage information (e.g. kWh or kWday or whatever). Using Node.js (running on the same Pi) all data is ‘RESTified’ enabling spreading out to the W3. To maintain privacy JSON web tokens are required every time the service is queried. Oh, and there is also a Pimatic plugin available (here)
Emon-server – 555 Timer as power usage sensor – [Link]
The MMA955xL platform as a sensor hub is an intelligent sensing hub with built-in accelerometer, signal conditioning, and data conversion with 32-bit programmable microcontroller and temperature sensor. In addition, it has a second I2C bus and one external analog input, which can be monitored using the on-chip Analog-to-Digital (ADC). This unique blend transforms Freescale’s MMA955xL into an intelligent, high precision, motion-sensing platform able to manage multiple sensor inputs.
The combination of low power consumption and powerful features means that the MMA955xL platform can effectively operate as a power controller for handheld units such as industrial scanners, Personal Digital Assistant (PDA), and games. The host platform can put itself to sleep with confidence that the MMA955xL device will issue a wake request should any external event require its attention. The MMA955xL device is programmed and configured with the codewarrior development studio for micro-controllers software. This standard integrated design environment enables customers to quickly implement custom algorithms and features to exactly match their application needs. Using the master I2C port, the MMA955xL device can manage secondary sensors, such as pressure sensors, magnetometers, or gyroscopes. This allows sensor initialization, calibration, data compensation, and computation functions to be off-loaded from the system application processor. The MMA955xL device also acts as an intelligent sensing hub and a highly configurable decision engine. Total system power consumption is significantly reduced because the application processor stays powered down until absolutely needed.
This device is optimized for use in portable and mobile consumer products that can make system-level decisions required for practical applications such as gesture recognition, pedometer functionality, tilt compensation and calibration, and activity monitoring. This may be applicable to tablets, digital cameras, smartbooks, laptops, gaming and security system as well as used in medical applications.
Intelligent Motion-Sensing Platform – [Link]
Bosch’s new SMA130 triaxial acceleration sensor provides information for infotainment and telematics applications in vehicles. “Until now, automakers have mainly used data from acceleration sensors for safety systems,” says Dr. Frank Schäfer, head of product management for automotive MEMS sensors. “The SMA130, on the other hand, delivers the data needed for eCall emergency notification and navigation systems.” The sensor measures acceleration along three axes arranged at right angles, as well as inclination, movement, vibration, and shock. The new Bosch acceleration sensor, based on MEMS technology, will go into series production in late 2015.
Acceleration sensor for infotainment systems – [Link]
±2% accuracy in a whole range of relative humidity measurement – that´s just one of several improvements brought by the third generation of miniature calibrated sensors from company Sensirion.
Even the actual series like SHT1x and SHT2x belong to a top in this segment. Forthcoming series SHT3x (SHT30, SHT31 and soon also SHT35) addresses mainly those of you, requiring maximum accuracy even in limit values (humidity below 10% and above 90%), miniature dimensions and ultra low power consumption. So a main difference of a new SHT31 compared to SHT21 is, that a typical +-2% is maintained in a whole range. Together with a precise temperature measurement in element we still have a possibility to simply compute a dew point, what´s one of the key parameters for ventilation control (HVAC, heat recovery). If it´s “only” necessary to guide a humidity not to exceed certain level, then you´ll probably also use the output „Alert“ pin, able to start interrupt in a host MCU for instance or directly control further devices. Output of the SHT3x sensor is the linearized value, which can be easily transformed to a final value (%RH, °C).SHT31 is available in 2 versions – SHT31-DIS-B with a digital output via well-proven I2C bus (2 selectable addresses) and also in a version SHT31-ARP-B with a linearized analogue (proportional) output. That´s why SHT31-ARP-B is an interesting alternative for direct processing in analogue circuits, as it contains 2 independent outputs with output voltage of 10-90% Vdd, responding to 0-100%RH and -45 to +130°C temperature. Digital output version also features wide possibilities of setting regarding measurement frequency, communication speed and other parameters.
Even the humidity & temperature sensors can be “3G” – [Link]
by Susan Nordyk:
Novelda offers two noncontact sensor modules—one for monitoring respiration and the other for detecting human presence at a range of up to several meters— for use in home automation, sleep monitoring, baby monitoring, and elderly care applications. Both sensors employ the company’s XeThru technology, which uses radio waves to “see through” a variety of objects, including lightweight building materials and blankets.
The XeThru X2M200 sensor module for respiration monitoring measures both the rate and depth of breathing to allow breathing patterns to be tracked in real time. With a sensor range of 0.5 m to 2.5 m, the X2M200 provides a reliable but nonintrusive way to monitor respiration and movement, capturing breathing patterns and frequency without being blocked by blankets or other obstacles.
Noncontact sensors monitor respiration and movement – [Link]
PyroEDU began in 2012 with the mission of offering free online courses teaching the fundamentals of electrical engineering in an approachable and entertaining manner. Rather than studying textbooks and advanced mathematics, students are taught using a learn-by-doing approach that follows four basic steps: introduce the topic, explain the theory, build an experiment to demonstrate the theory, and offer real-world examples to demonstrate how the topic is utilized today. Students can interact with other students and the instructor via the PyroEDU forums or by joining one of PyroEDU’s hosted classrooms on uReddit or P2PU.
PyroEDU is currently teaching its sixth course, An Introduction to Sensors, covering a wide variety of sensors from motion detectors to temperature sensors. This sixth course is the capstone in the Introductory Series of courses PyroEDU offers (visit http://www.pyroelectro.com/edu/ for a complete listing of courses in the Introductory Series). Working with The Gadgetory, an online electronics retailer, PyroEDU will be offering a comprehensive kit that includes all the parts necessary to complete the Introductory Series of courses. More advanced series are planned in the future which may include courses in animatronics and robotics.
An introduction to sensors – [Link]
by Steve Taranovich @ edn.com:
Gas sensing techniques are continually being investigated to improve selectivity and sensitivity of identifying different types of gases. There are resistive gas sensors, quartz crystal microbalance, direct thermoelectric, electrochemical cell and other exotic types such as MEMS-tunable Fabry-Perot filter spectral sensors with lead-selenide detector and pulsed broadband infrared emitter light source. The ams sensor is a resistive type.
The resistive sensor design relies upon heating circuitry for temperature control of the entire system. There are different types of resistive gas sensor techniques and construction. Some are based upon metal-oxide (MOX) thin films which are small in size, low-cost, and low power as well as able to use low-power integrated analog front ends.
ams develops MEMS VOC gas sensor – [Link]