A sound activated switch project by Rajkumar Sharma of Electronics Lab: Clap switch/Sound-activated switch designed around op-amp, flip-flop and popular 555 IC. Switch avoids false triggering by using 2-clap sound. Clapping sound is received by a microphone, the microphone changes the sound wave to electrical wave which is further amplified by op-amp. 555 timer IC […]
Category Archives: sensors
Reverse engineering a wireless soil moisture sensor
Ray Wang at Rayshobby has been working on reverse engineering a wireless soil moisture sensor. He writes, “At the Maker Faire this year I got lots of questions about soil moisture, which I knew little about. Recently I started learning about how to build my own soil sensor, and came across this cheap 433MHz wirelss […]
Temperature and humidity measurement with DHT11
Ondrej Karas of DoItWireless writes: This article describes temperature and humidity measurement with DHT11 sensor connected to TR module. Circuit diagram is very simple. You need only power supply for sensor and one wire for data line. This line has to be “pull-uped” – sensor has open colector output.
Build an Arduino based sonic pest repeller
Just in time for Summer, here’s a design for a sonic pest repeller. Carla Schroder developed this project which uses an Arduino Uno along with the WAVE shield and a Maxbotix ultrasonic rangefinder. This simple yet reportedly effective design senses critters nearing your garden plot and plays sound files (stored on an SD card) intended […]
Temperature compensation for an Arduino ultrasonic distance sensor
Sverre Holm writes: Ultrasonic distance sensors can find the range out to 2-4 meters and are popular in e.g. robotics. Here I look at how the accuracy can be improved by compensating for the variation of speed of sound with temperature. It actually varies quite a lot in air and around 0 C it is: […]
Impact, vibration and ultrasound sensing with PVDF Piezo sensors
Shabaz over at Element14 writes: This post is about an interesting, low-cost sensor that doesn’t need much processing to use, and has some unique characteristics – a PVDF (polyvinylidene difluoride) Piezoelectric sensor. The sensors looks like a small strip of plastic, and can be used for detecting movement or vibrations even into ultrasound. Such devices can […]
A simple posture sensor
Here’s a simple cure for your posture and the back pain blues, a posture sensor by Wingman: The simplest distance sensors are ultrasonic or infrared sensors. I went with a SR-HC04 because it is cheap and sufficiently precise. There are no special requirements to the controller so I am using an Attiny85. A small piezo speaker provides acoustic […]
Arduino based auto trigger spray keeps cats at bay
Curiosity killed the cat, but this project only sprays them with water. Tinkernut posted this humorous project useful for animal control in the kitchen. It uses an Arduino/PIR combo to sense motion and activate the auto trigger on a Raid spray bottle (of course, after emptying and thoroughly cleaning the Raid bottle.) When strategically placed […]
MSP430 and a HC-SR04 ultrasonic ranging module
Juan Ignacio writes: A while back I bought an HC-SR04. It sat in a box until yesterday when I tried to use it with an MSP430G2553 but unfortunately it wasn’t working. I used Energia to program the Launchpad but I wasn’t getting any response from the device. I hooked up my Logic analyzer to see what […]
Improving the HC-SR04 ultrasonic sensor
Emil has written a post on improving the HC-SR04 ultrasonic sensor. Via the contact form.
Open source data logger for biodiversity research
Ed Baker of the Natural History Museum, London, UK, has published a paper outlining his build of an open source hardware data logger for scientific purposes. “Proprietary data loggers can be expensive – for example a three channel data logging system is available from Alphatemp for £465.00. Such costs make large scale deployment of such […]
Breakout module for Si7005 temperature and humidity sensor
Raj of Embedded Lab has written up documentation on his Si7005 breakout board: The Si7005 is a digital relative humidity and temperature sensor from Silicon Labs. It integrates fully factory-calibrated humidity and temperature sensor elements with an analog to digital converter, signal processing and an I2C host interface in a single monolithic CMOS sensor IC. The Si7005 […]
TCN75A Temp sensor investigation
Charles writes: Upon receiving the SOIC breakout boards I took one and carefully used a Dremel to mill out the package outline. I had started to design my own PCB but I abandoned that because I didn’t want to wait for fabrication. I mounted the new sensor on it’s vented PCB then plugged the sensors right […]
Magic Mote wireless sensor v2
Tom posted an update on his Magic Mote wireless sensor we covered previously: Here is Version 2 of the Magic Mote PCB. The tactile switch is more accessible at the side of the board, the programming/serial header is now IDC6 compatible, and there is improved isolation of the ground plane under the watch crystal.
LuxBlaster: Arduino controlled light sensor/response device
Techbitar writes, LuxBlaster is an Arduino gizmo that detects and tracks the most intense light source then sends back an intense light in the same direction. Beware, rude drivers. The LuxBlaster is coming!! When you drive at night, every once in a while a car will approach you from behind with its annoying high beam […]
Inductive loop vehicle detector v2.1
Trax of Elektronika.ba has written an article detailing his inductive loop detector that uses PIC microcontroller and Colpitts oscillator with a large coil buried in pavement to detect vehicles: Inductive Loop Detector works by detecting an inductance change in wire loop (coil) that is buried in road. It does that by measuring the frequency of the internal […]
DEFCON 21: Arduino based vehicle tuning device
In this presentation from DEFCON21, Albert Garcia Illera and Javier Vazquez Vidal discuss the development, Houston TX enclosed auto transport and operation of an Arduino based device for controlling automotive functions in 2010 and newer model vehicles that use the K-Line protocol (although we’re told it could easily be modified with newer protocols.) Additionally they […]
Arduino Bot tweets temp/humidity updates
While testing out various sensors, Steve from Hackshed.co.uk thought it would be fun to make the Arduino actually tweet out what the current status of our office is. “The Arduino records the current, minimum, maximum and temperature change as well as humidity and then sends out a tweet to a Twitter account with an update […]
SquareWear Mini chainable color LED matrix and animation design tool
Ray Wang writes about his recently completed project, the SquareWear Mini with All-New Chainable Color LED Matrix, and an Interactive Animation Design Tool. The goal is to make standalone programmable color display gadgets. The LED matrix is chainable and can be seamlessly extended in both X and Y directions. The SquareWear Mini is essentially an […]
project ECHORD – Riverwatch
Eduardo Pinto informs us that the Riverwatch crew has finished the first phase of their project ECHORD – Riverwatch and have posted a first version of their site. The project is developing a Marsupial Surface-Aerial Robotic Team for Riverine Environmental Monitoring. One of the main goals of our project is to make everything open source […]