I've been planning for several weeks to build a detector for bicycles
and cars using garden hose, ... anybody will drive over a garden hose.

I looked at pressure sensors, but the amount of amplification needed
between the sensor and the PIC looked daunting.  I'm no analog guy.

I looked at a microphone on the end of the pipe, to catch the pulse of
air.  That seems to be doable, there are modules with preamplifiers,
but the signal processing will be irritating.  There might be false
triggers due to thunder or kangaroo grazing near the microphone.

I looked at a salt water filled hose turning upwards into a narrow
chamber with a few resistive sensors (bare pins).  The compression
pulse should cause sloshing.  Maintenance is a problem; the water will
slowly evaporate.  At least it won't freeze here.  ;-)

Presumably there's some electromechanical solution as well.  An air
pressure switch.

--=20
James Cameron
http://quozl.linux.org.au/
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