John,
Right now I am just experimenting with getting higher volume and faster
production and trying to understand the process. The power supply in
the example I stated was not current limited.
The way I understand it, Ole Bob's method of limiting the size of the
cathode is mainly to limit the amount of silver wasted by the reaction
of the silver ions at the cathode. The smaller the cathode, the less
wasted silver. As the silver ion concentration gets higher, you will
still be putting net ions in the water instead of plating them out on
the cathode. So, the effective reaction happens faster and lasts longer
(than it would have with the large cathode) at the end of the process.
Increasing the cathode size reduces the resistance of the cell so that
your initial current will be higher so you will get to current limiting
faster without using a higher voltage. The reaction happens faster at
the beginning of the process.
The point of the large anode area is to be able to draw a large current
without having a large current density at the anode. Not absolutely
sure about this but I think that this keeps the silver ions from
agglomerating. It also reduces the resistance of the cell so the
reaction starts fast.
Another point of Ole Bob's process is that after you characterize your
cell, if you don't change any parameters the reaction will proceed at
the same rate so you don't need to continue to monitor it each time, you
can just run it for the set amount of time determined by the initial
runs. The only difference is that you would have to adjust for the
initial conduction of the Distilled Water if it was different. If it
was twice the uSiemens value, the reaction would take one-half the time.
So you can just time the reaction instead of "baby sitting" it. You
could still shut down the cell using some sort of electronic sensing
too. Characterizing the cell just shows you what is happening and
allows you to optimize the operation for this cell.
Sounds like you have developed a great system. One question I have is
that initially you used 100ma at 8 hours to get 5 gallons of 25uS CS,
later you used 40ma at 5.5 hours to get 5 gallons of 28us CS (about the
same conduction reading, but the second condition is taking less time
and current). What do you attribute that to?
Perhaps Bob (or anyone else) can comment too.
Dan
HRBE wrote:
Dan,
I always use a current controlled power supply, Bob controls the current
by limiting the size of the cathode.
I couldn't sit and baby-sit the process as I do have other pressing
things to do!
I ended up increasing my brass cathode area to the same surface area of
the anode, controlling the current to 40milliamps at 30 volts DC.
Is your power supply current limited?
I end up with 5 gallons of perfectly clear CS giving me a reading of
28uS/cm on my Hanna PWT in 5 1/2 hours.
My 2 cents worth!
John in Australia
----- Original Message ----- From: "Dan Nave" <[email protected]>
To: <[email protected]>
Sent: Wednesday, May 10, 2006 1:34 PM
Subject: CS>wide anode and narrow cathode brew
Ole Bob you are a genius!
I finally got a larger piece (20 gage sheet - 3 ounces) of silver ($70
;-( and my own cheap Harbor Freight Tools current meter ($5.00 ;-) and
tried out my first cell with the wide anode and narrow cathode. The
sheet anode is 6" x 3" and the cathode was a piece of 12 gage copper
wire about 6" long. I had 5.5 inches of the anode in the distilled
water. Incidentally, I made 32 ounces, 1 quart, and the bottle was way
too small for the anode but I made it anyway. I brewed it for 1.25
hours and stopped with the current at 13.25 ma (@33.8 VDC). This
comes out to about 6.625 ma for 1 hour if you average it out roughly.
Rule of thumb calculation gives about 28 ppm liberated silver, and PWT
says 27.8 uS. I normally get about 22uS. The current line on the
graph was still going straight (not bending to the right) but I
stopped it anyway because of the PWT reading. There was some dark
buildup on the cathode and it turned silver from plating, but the
residue didn't seem excessive compared to the 1 ma current controlled
same size anode/cathode system I usually use. The Tyndall was very
minimal, can't see it in normal light and appears about 1/4
(subjectively) of what I normally get. This has a slight tint to it.
I know that this first attempt was very sloppy, but I was surprised at
the speed of the brew, the high PWT reading, and the low Tyndall.
Dan
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