On 9/25/2011 8:46 AM, Robert Green wrote:
wrote in message

stuff snipped

I dunno. I distinctly recall seeing a program about a flood and people
watching from a tall hotel building. When the water reached a certain
level, the horns of the cars in the hotel parking lot began sounding.

Why would watert short the horn relay, but not short out the battery
so the horns couldn't sound. Why wouldn't the headlights go on, and
the trun signals, etc. Why the horn?

Beats me. All I remember is the survivors making a point of how eerie it
sounded in a hotel without power and not much noise when the car horns
started going off in the rising waters, one after the other. Then they
starting gurgling as the water reached the horn's diaphragm and finally went
silent. I know they're relay controlled so I suspect that's the component
that caused the horns to sound. How, I couldn't say.

I'd guess it had to do with car alarms.


Perhaps the weight of the water on the steering wheel horn button is
what made the horns sound.

I'd rate that scenario "not likely" I'm afraid.

While I believe that most door and window circuitry is rubber-booted and
generally weatherproof,

I'm not saying anything is weatherproof, just that copper conducts
electricity better than even dirty water.

That doesn't matter, though, in something like a PC circuit board or perhaps
even a relay. That's why so many cellphones die when dumped in the sink or
worse. Flood waters on city streets are probably a hell of lot more
conductive than clean water.

To prove a point I've already put a working video game pc board into
water and it kept working. The trick is that I didn't get the sensitive
parts like the clock/crystal wet. That will stop it from working, as I
eventually demonstrated. And just for the record, the pc board worked
fine again after it was dry.