Earth Electrical Energy Datalogging Experiments

[MileHigh]

Hi Jenna,

I glanced a few times at this thread and just have a comment or two, you may have even heard them before.

My suggestion is to also record your power measurement every day in addition to your waveforms.  Perhaps a 10 Mohm 10-turn pot would do the trick for you.  You first set up your waveform display.  I believe it also gives you the RMS voltage on the display, which is perfect.  You have your waveform set up and then connect the 10 Mohm potentiometer across the leads and then turn the potentiometer until the RMS voltage drops by one half.  Then you make a quick measurement of the resistance setting on the pot and record that.  The maximum output power that day is then the lower RMS voltage measurement squared divided my the resistance setting on the pot.  It will probably measure somewhere between microwatts and miliwatts.  The measurement of the pot setting is a big bonus, that is giving you the output impedance of your earth battery.  That is a very important measurement of the relative strength of the power source.  The lower the output impedance the better.

Anyway, you may find a corelation between the relative moisture in the soil and the output power and impedance measurements for your earth battery.  Larger buried anode and cathode setups should also give you more power generation and lower output impedances.

The only thing that I am not sure of is the right value for the potentiometer, I would imagine it is somewhere between 100 Kohm and 10 Mohm.

Anyway, don't let me disrupt anybody's projects but if there are keeners out there these measurements are really informative and tell you about the state of being of your earth batteries.

MileHigh

[IotaYodi]

That is excellent Milehigh! 
Whats your suggestion on the pot? Standard runs from about .5 v to 1 volt

[IotaYodi]

Camera cell phone into a webcam.
http://www.youtube.com/watch?v=Ar2-GILSg_c&NR=1

Interesting camera cell phone into wireless oscilloscope.
http://www.youtube.com/watch?v=PrOs2TiyGy4

[MileHigh]

Iota:

If you experiment with discrete resistors and observe the RMS voltage (should be a true RMS meter) drops that will give you a feel for what's going on.  Don't be surprised if a 10K resistor reduces the waveform to almost nothing and don't worry about it either.  It just means that you have to try a much higher value resistor.

Keeping it simple, suppose that you find after measurements on a few setups over a few days that on average about a 1 Mohm resistor makes the RMS voltage drop by about one half.  In that case the "Cadillac" solution would be to get a 10-turn wire-type 5 Mohm potentiometer.  There are also little PCB-mount 10-turn potentiometers.  They look like little blue boxes and you can adjust them with a jeweler's screwdriver and are much less expensive.

Perhaps another option would be to have a few different ordinary single-turn potentiometers.  The only reason for using a 10-turn pot is to get more measurement accuracy to detect subtle trends.  Just some ideas.

MileHigh

[jeanna]

Milehigh
I am not sure I can read less than millivolts.
I think rms is not relevant because this is not sinusoidal at all. If it is then it is not natural and we must ignore it.

Thanks,
If you want to join us, I will be delighted to see the results you have on your special one with the pot and
much more interested in the one that is done simultaneously with a scope (if you have one) on 2 probes one copper and one zinc covered iron.

I will not be coming inside, but I am not about to make this more complicated than it already is.
I have 2 stubblefield coils added to each end of 2 probes and that is what interests me. (My personal interest)
I am reporting on the plain ones for the sake of the datalogging experiment.

thank you,

jeanna