Doug,

When you put in the regular air freight part you eliminate any 
explosives but on site generated oxygen and hydrogen.

When you set the cost limit at $2,000 you eliminate any drop 
hammers or devices weighing at 500 to 1,000 pounds unless they 
are extremely simple.

If you really want a device in that price range I think you 
should reconsider using a 2 or 3 liter bottle with enough water 
in it to discover a coating around a bit of calcium carbide and 
generate C2H2 when it is dropped in the bottle after the bottles 
is set in the ground and covered up to the cap by unskilled 
labor. The Forman or Preston in charge loads the calcium carbide 
pellet that is coated in something to keep it from generating 
C2H2 for a few minutes and finish covering it up and wire it for 
firing.

There needs to be a pressure sensor in the lid of the bottle to 
let you know when it has enough C2H2 to give the desired results.

I think it can be done as safely but you can't ship calcium 
carbide air freight. But it is a lot cheaper than you price range.

I don't think a kinetic device that put out and  absorb the 
energy of sledge hammer over and over can be made for $2,000 
with out an explosive component.  I have seen first hand what a 
sledge hammer can do.

If you don't want explosives I think you may be suck with a 
sledge hammer with a #2,000 cost limit.

Gordon

Doug Crice wrote:
 >
 > Doug Crice          http://www.geostuff.com
 > Wireless Seismic            http://www.wirelessSeismic.com
 > 12996 Somerset Drive                phone 1-530-274-4445
 > Grass Valley,  CA  95945  USA    fax 1-530-274-4446
 >
 > I have greatly enjoyed this discourse on a better exploration 
seismic
 > source, and look forward to more ideas.  To kind of remind 
folks of the
 > specifications, I would like to repeat and expand them.
 >
 > 1) A person ought to be able to carry it around (and be air 
mobile by
 > regular air freight).
 > 2) It needs reasonably high frequency output (ping instead of 
thunk)
 > 3) Build it for $1000-$2000 (cost, not sales price) in lots 
of 10 units,
 > using commercially available and machined parts and normal 
labor rates.
 > 4) It should be safe, even when used by students
 > 5) There should be no significant regulatory issues (a 
problem with
 > dynamite, the perfect source)
 > 6) Operating supplies available in third world countries.
 > 7) It needs to work better than a sledgehammer used with a 
seismograph that
 > can stack multiple impacts.
 > 8) Because the source will probably be used in a repetitive 
fashion, it
 > needs a reasonably fast cycle time (many seconds, not many 
minutes).
 > 9) The seismic signature should approximate a zero phase 
wavelet, which as a
 > practical matter; means the energy prior to impact should be 
comparatively
 > modest.
 > 10) Good ground coupling is needed. In the case of a 
sledgehammer, a metal
 > plate is placed on the ground as a target. In the in-hole 
shotgun, a hole is
 > augured just big enough to hold the device below the soft 
topsoil and
 > preferably watered.
 >
 > The crossbow idea is equivalent to the "elastic wave 
generator", powered by
 > the large rubber band. Existing units weigh a couple of 
hundred pounds, but
 > it's got me thinking about a portable version.
 >
 > The variations on exploding bottles don't seem to meet the 
requirements for
 > reasonably safe operation. Sure, a careful user would be 
safe, but we are
 > talking about students and third-world laborers.
 >
 > An earlier variation was the "vacuum assisted weight drop". 
It had a 6 ft (2
 > meter) long tube about 6 inches (15 cm) in diameter with a 
100 pound steel
 > bullet inside. The bullet was pushed up with air pressure, 
then evacuated.
 > When the tube was full of vacuum, it was released and 
accelerated by its
 > weight and by atmospheric air pressure. At the bottom was a 
100 pound anvil
 > and plate combination pressed on the ground by the weight of 
the whole
 > mechanism. With equal weights for the piston and anvil, it 
didn't bounce
 > (think of that ball bearing toy). The VAWD worked reasonably 
well, but
 > weighed 1000 pounds and cost over $10K 20 years ago. Using 
air pressure as
 > the accelerant provided a nice signature, since the force was 
external to
 > the system, though when you released the piston, it instantly 
lost 100
 > pounds of weight, providing the equivalent of a negative 
sledgehammer blow.
 >
 >
 >
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