Sensor Arrays, Ctd.

Humidity sensors are typically more expensive than temperature sensors and are more complex to design/build a circuit around. As the price goes up, the fewer additional parts are needed but once the price gets beyond the $50 range, I'm not that interested. For about fifteen dollars and about five more in additional parts, a decent humidity sensor can be built. I plan to do some mapping in my home but I am guessing that there are probably not pockets of high or low humidity in my house and having 2-3 max humidity sensors will be plenty.

A few weeks ago I was reading and article in MAKE magazine about a guys who wanted to lower his clothes dryer electricity bill so he sought to use hot air from outside or the attic. I thought it would be a cool idea if you lived in a place with dry heat but don't think it would be feasible here in Florida. At some point I might try it just to see if really hot humid air could successfully contribute to lowering drying time. I think the key is to find a way to take the water out of the air quickly.

Any ideas?

Sensor Arrays

For my home automation project I am designing some sensor arrays to collect various type of data. Examples of sensor types include temperature, humidity, light intensity, proximity, sound and possibly a RFID reader. Each sensor array will be connected to an XBee Series 2 transceiver in order to be linked to the wireless network. When possible, a sensor will be designed to use an energy harvester which will allow the sensor array to run for long periods of time between charges.

An example of a typical array will be one with a temperature and light intensity sensor included in the circuit. Placing temp/light sensor arrays throughout the house will allow me to track hot and cold spots and help determine the best way to keep the house cool while using the least amount of energy. Living in Florida, it is rare to be concerned about it being too cold in the house or how to keep the house warm enough to fight off frostbite.

Typically in my house the master bedroom stays about 3-5 degrees cooler than the rest of the house. This is perfect at night as my wife likes to sleep in a cooler room. However once we are up in the morning and either at work or working at home, very little time is spent in the master bedroom or bath. If the cold air being delivered to the bedroom could be channeled to the living room or the office, it would keep the part of the house being utilized cooler without lowering the thermostat.

Using the light intensity sensors will help map out the brightness of the rooms being used at particular times of the day and determine which areas need additional light as it gets later in the day. What I hope to accomplish is to inexpensively add light to the kitchen/dining room by building lights using 20 Watt LEDs that would dim/brighten based on the amount of light needed. A 20 Watt LED has approximately 1000 lumens, which in incandescent wattage amounts is approximately 100+ Watts. A couple of LEDs could keep a high ceiling, open area nice and bright throughout the day and night.

ZigBee Wireless & Python

I recently became interested in ZigBee Wireless Radios as part of Home Automation and tracking home energy usage. ZigBee is a wireless mesh networking standard intended to be simpler and less expensive than other WPANs, such as Bluetooth. They are very useful in in wireless control and monitoring applications due to the low power-usage which allows longer life with smaller batteries, and the mesh networking provides high reliability and larger range. My first exposure to their usage was a hack to the popular Kill-A-Watt power monitor which adds wireless reporting and is called the Tweet-a-Watt.

After implementing the hack and doing some measurements throughout the house I decided I wanteds to expand the monitoring of my energy usage and started looking for a reasonably priced kit I could have some fun with and learn about my energy usage. After one false start I came upon Digi, which manufactures a line of wireless radios and some cool evaluation kits. I researched three of the kits and decided on the iDigi™ Wi-9P Starter Kit ZB.

My main reason for going with Digi and this kit is the ability to use Python in controlling the reporting of the data. There is plenty of documentation in getting the network up and running, monitoring and modifying the presentation (reporting) and adding sensors to the mix. Python scripts are written and then uploaded to the network using the Embedded Gateway Configuration and Management web page.

My network is up and I have two sensors sending data, one sending temperature and light and the other sending in just temperature. As I make additons to my network, either by adding additional sensors or enhancing the reporting I will include steps and screenshots. Stay tuned as I am just getting started.

Note: I am not affliated with any of the companies mentioned in this blog and all products written about were purchased by me.