Another great example of a Sherlock Ohms story where the engineer had to figure out something very obvious that is easy to overlook -- that is, that most wooden furniture has metal nails. Good sleuthing.
Every time a parameter is changed, you have to reanalyze the test. Something as simple as a table might seem innocent, but I will be checking out my tables and other fixtures when I don't get desired results with no explanation. Good job!
Growing up on a small farm in Eastern Oregon, I learned how to fix a lot of things with tools/supplies at hand (I have a pickup and baling wire story). It's served me VERY well in this career and in my hobbies.
Yes, it was a good job, Warren. The trick is to think of the hidden metal in a wooden table. I remember in the late 1970s, Sandia Labs was testing aerospace equipment and needed a mammoth wooden structure -- about 100 yards long, 50 yards wide. It was built entirely with wood. No nails because metal would interfere with the testing.
On the southwest corner of the campus at Worcester Polytechnic Institute (Worcester, MA) stands a stone building used some time ago as a magnetics and electricity lab. It contains no magnetic materials. Read a short history and see a photo here: http://www.wpi.edu/about/tour/skull.html. The street-car line no longer exists. I cannot vouch for the veracity of stories about the Skull society and any "secret" ceremonies.
I heard a story about engineering students who created a wireless robot that would crawl through metal pipes. The robot would into the pipe, but at exactly the same point it would stop communicating. Turned out the pipe formed a nice waveguide and acted like a dead short for the RF, so communications ended abruptly. My memory is a bit hazy, so maybe some other waveguide effect caused loss of comms--I'm not a microwave guy.
Reminds me of an occurance years ago when I was an automated sewing eqipment technician. This was back in the day old fashion "electric eye" sensors were still crude. An operator reported a problem that the machine seemed to have a mind of its own and would activate for no apparent good reason. After severl attemps at adjusting the sensitivity of the "eye" and various other adjustments the problem would appear to be resolved only to re-occur the next day. This went on for several days and I finally recruited the assistance from one of our engineers. We both went through every conceivable theory and process as to what could be causing the problem when out of the blue he asked me to walk away from the machine. "Miraculously" the problem stopped only to start again as I got closer. The engineer then asked me to change my shirt, without giving any reasonable explanation. Being in a sewing plant this was not hard to do. I simply walked to the end of the line and chose a nice black sweatshirt that had just been completed. Problem fixed. it seemed there was just enough sunlight from a nearby window that would reflect from my previous white shirt just enough to cause the sensor to activate. No problem on a cloudy day but if clouds were moving across the area the reflection problem seemed to just be random. This was another example of a much simpler overlooked but not so obvious baffling situation. Final solution---put a piece of cardboard over the window. There, that fixed it.
Some years ago we were involved in certification of an ISM band product at an FCC approved lab. One of the resident engineers gave me a tour of the facility and showed me a large test room on the roof of the building built mainly of wood. He proudly explained how the structure had been assembled with no metal fasteners anywhere. I would expect the test lab to have a sense of professionalism.
I love stories where people make changes in someone else's project without thinking of or knowing of the damage they could do. I unplugged an extension cord that ran to a copier so I could move a desk to another area and then I was going to replug it. Harmless right.
Well someone else had already disconnected the copier and had a computer plugged in. I pulled the plug and heard one of the book keepers say, "Oh no. I just lost March." I was tempted to quickly reconnect before I was found out, but confessed and had to indure icy stares for a good week or so.
Festo's BionicKangaroo combines pneumatic and electrical drive technology, plus very precise controls and condition monitoring. Like a real kangaroo, the BionicKangaroo robot harvests the kinetic energy of each takeoff and immediately uses it to power the next jump.
Design News and Digi-Key presents: Creating & Testing Your First RTOS Application Using MQX, a crash course that will look at defining a project, selecting a target processor, blocking code, defining tasks, completing code, and debugging.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.