On Mon, 30 Nov 2009 10:31:12 -0800, Jim Lux
wrote:



3 9V batteries in series makes a fine source to actuate a sprinkler
valve. Put a 0.1 uf (or thereabouts, non critical) capacitor across the
pushbutton contacts to make it last a bit longer.

Got a little further today. It takes too many hands to twist the
valve, fiddle with the reel and aim the device. I black vinyl taped a
micro switch to the valve assembly with ONE 9 volt battery so that I
can thumb it to launch. I also moved the open face reel back to the
valve end of the barrel and fabricated (more black tape & paperclip)
an eye to pass the line through so that line retrieval with the reel
is less awkward. Today's final test was conducted in the dark so I was
unable to see much. I launched nearly 90 degrees and it was gone for
several seconds so I expect it did well.

VK2KC emailed me with some advice. He pointed out that it is usually
better to launch from the woods to an open space. I expect that will
be the case.

It seems to me that this device consists of three components: Barrel,
Valve and accumulator. It seems that to change to launching tennis
balls would be a matter of fitting a 2-1/2" barrel. I doubt that I am
going to find that in my area but I will keep my eyes open.

Tomorrow is another day!

John Ferrell W8CCW