Throughout my life I’ve been making things: battleships from cardboard boxes as a child; software and systems as a professional; photographs, knives and sculptures as an adult. As a result, I’ve continually dreamed and schemed to acquire tools. My first toolbox was tiny and sparse, dwarfed by comparison to Mom’s which was chock full of the things she used to maintain our home and car. High school in the 1970s exposed me to a machine shop and a wonderful teacher (thanks Jim Koutsoures!) as well as to other industrial arts. Computers got the better of me though and I’ve spent my career in the digital realm.
In 2004, a chance visit to eBay awakened the old dream: I spotted an auction of a small metal lathe which was nearby. I was first astonished that a lathe would be on eBay, then curious enough to go see it. Well I didn’t buy that lathe, but some years and thousands of pounds of old iron later, I finally have the small shop that has been a dream since childhood. Actually it is more than just a small shop, it has been a labor of love and I am profoundly grateful for my wife’s incredible support and understanding. As an artist, she truly understands the need to create in the physical realm.
I like to monitor the temperatures in my shop and I receive the occasional question about how I gather these measurements. Well, in stark contrast to expensive commercial monitoring systems, using commonly available parts one can construct a reliable building monitoring system for the cost of an old PC and about $150 worth of sensors. Here is an overview of the components used to build this system.
Sensors are from iButtonLink and are based upon the 1-Wire network which uses simple twisted pair wiring to connect sensors in a variety of topologies. I used an old Amphenol 6 port RJ45 harmonica and wired the ports into a passive hub configuration to create a star topology. The PC connects to the iButtonLink LinkUSB USB master which is in turn plugged into the hub, as are the sensors. All sensors are iButtonLink T-Probes except for the iButtonLink MS-TH which provides both temperature and humidity readings. Note that the DS2438 temperature sensor used in the MS-TH is not as accurate as the DS18B20 used in the T-Probes—a minor nit.
The PC runs Linux (I like CentOS) with OWFS 1-Wire software to read from the sensor network and RRDtool recording/graphing software. A simple shell script called from cron on 5 minute intervals provides for regular data collection.
When something is desired, one is aware of its absence;
when something is not desired, one is aware of its presence.
Desire and attachment disturb peace: they drive it away.