Circuits are Hard. . .

I had to eat my words, and swallow my pride today. Le sigh. I got into work this morning to find half of the lab flooded. The water system was overflowing. I turned off the water and put the systems on stand-by. I figured something was wrong with the sensor that controls the shut-off. I set-up a technician visit, and then the "yes, I really can do anything" man showed up. He's a "PhD'ed" individual with huge reserves of raw brain-power. So Mr. Amazing climbs up onto the lab bench, opens the tank, pulls out the sensor (which is about 3.5 feet long), climbs down, and proceeds to show me how it works.

The sensor is a series of resistors in parallel with a series of switches running between them like ladder rungs. As the water-level rises, the magnetic float rises too and closes a switch at for every 5% of the tank that fills. This shorts the circuit and allows the sensor back in the wall to sense how much current is flowing, and thus how full the tank is. He proceeds to check the magnetic sensor by moving it up and down the circuit and reading what the machine says. That seems to work just fine.

Mr. Amazing goes back to the "box" and starts looking at the wiring. He takes apart a plug and notices copper chloride (corrosion from getting wet) sitting in the bottom. He determines that this is the cause of the problem. He says he'll go to Radio Shack and buy and new one, and in the meantime I need to figure out how the circuit works. . .

He comes back, fixes it, and we're back in business. As for me - I figured it couldn't possibly be that simple. I over-analyzed it and finally asked him to draw it for me. Damn-it, I would have been correct! Chalk one up to self-doubt. Ach, I wish I were smarter.