On another note, the "beeping" sound of common appliances need to be toned down. I once took apart a microwave and removed the speaker for that reason. A volume control is a must. Also, remove the last beep of the warning cycle is key.
Just Like Father Guido Sarducci said about the birthday song, it's too long. Remove the second "happy birthday to you," and it's tolerable.
Tool_maker's story made me sit up straight. The possibility of the "bug" in a system being an actual bug is an old joke in electronics. It's a joke because the actual occurrence is more than a pun, and has actually happened, according to my tech support friends back in the day.
When I first got an oven with one of those touchpads, I was happy--thought it was cool. Now, 10 years later, it's failing--you have to push harder and harder to activate the contacts underneath. Sometimes the timer just doesn't work, since that's the function I use at least once a day.
@Elizabeth: You find it hard to believe that a bug could be the source of the problem. I saw an ant colony bring an M-1 tank to a standstill. It had nothing to do with engineering and I hope the editors see fit to let this story fly.
We were on an operation in the jungles of Vietnam and my Armored Personel Carrier was following behind a tank as it busted brush. It approached a tree with a large cluster of red/orange leaves, that appeared to be dead. When the tank hit the tree, the red/orange fell out of the tree and covered a good portion of the tank. It wasn't leaves at all, but a colony of army ants. The ants quickly began biting any warm body they contacted, which was about 6-8 soldiers in and on the tank. Now if you were dealing with just a few it was no big deal and you could swat them off, but when there were hundreds the pain was unbearable. They quickly got under your clothes and the only thing to do was get out of the area, get out of your clothes and start beating them off.
So here sat the tank while the whole crew bailed out and off the tank pulling off their clothes while swatting ants off each other while jumping and screaming. You would be amazed at how fast those ants and their victoms can move. I saw one guy pull everything off without undoing a button or zipper. After the fuss had settled we poured diesel fuel around on the surface of the tank which seemed to solve most of the problem, but periodically for several hours we heard yelps and saw swats as the tankers discover ants not detered by the diesel fuel.
So when someone tells me a bug can mess up the works, I remember when I saw them stop a machine of war.
tekochip, sounds like you did a much more thorough job of designing--and testing--those interfaces than some of the examples we've heard about here. I like your "Twister" description--makes it easy to visualize.
My uncle was in the Signal Corps in the Pacific in WWII. He used to tell me about how the rats would try to get into the transmitters to get warm and dry out. Of course the results of a rat getting across a several KV plate supply is somewhat more spectacular than an insect across a low voltage switch.
I had a similar experience when I lived in the Dallas TX area. My house had a LV lighting system (12VAC) around the exterior and walkways. There was a 300VA or so transformer that fed the system, with 2 separate outputs (dual secondaries on the xfmr). I started having intermittent outages on some lights, but the bulbs were OK. There wasn't much voltage at any of the fixtures on one of the outputs. I traced the apparent short down to a specific point (all wiring as buried so I really wanted to only have to excavate where the problem was likely to be) by locating the first fixture that had minimum VAC at it. I started to dig, and was quickly attacked by a bunch of fire ants! After I did away with them (took a full day for all to die), I dug down and found their nest had been located surrounding a splice insulated with some badly chewed away electrical tape. Thus a short between the conductors was created. Unfortunately, the long-term overload had weakened the one secondary; a couple of weeks after the wires were re-taped (very heavily!), that secondary winding opened up. I sent it back to the manufacturer, who was amazed that the primary protection hadn't tripped, and so the fusible link inside the winding had opened. The resistance of the wiring to the short location was apparently just enough to let the winding overheat without tripping the circuit breaker in the transformer primary. They sent me a brand-new transformer at no charge! When a similar outage occurred some time later, I concluded that the ants really loved the AC field (maybe got high on it!), and made future repairs with even more protection on the splices.
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