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[Bill Jones <billj AT harborside.com>]

Here's a link to a page where you can see my new water pump:

http://home.earthlink.net/~clanl/pump.jpg

The first check valve, mounted directly at the bottom of the pipe, is 
oriented horizontally.  It allows water to flow only inward from the side.

The second check valve, mounted after the two 90-degree elbows, only 
allows water flow upward and out.  This is the return line, now fitted 
with a length of hose.

What's to understand?  When you submerge the unit upright in water, it 
fills through the first check valve.  When you blow air into (the hose 
now connected to) the top, water has nowhere to go but downward, around 
the elbows, and up through the second check valve.  It may not be enough 
in one pulse to make it all the way to the top of the hose, but after a 
couple of puffs of air it shoots out and hits the ceiling, since the 
second check valve prevents backsliding.

So the only fancy part is to figure out how to repeatedly send it a 
measure of air, and disconnect the air to allow refilling.  The patented 
versions have a quick pressure release valve, which takes care of the 
disconnect, so they just need to be sent intermittent air pulses.  I'm 
making mine the best way I know how, with an electronic water level 
detector to sense when the chamber empties, and a delay circuit that 
turns on a 3-way solenoid valve for the fixed-length refill interval.  
Mine can be attached directly to a wind-powered compressor, because it 
will wait as long as necessary during light winds for the chamber to empty.

So I'd appreciate any suggestions for how make compressed air pulse 
rhythmically.  Then no electronic control is required.

Bill
S. Oregon coast