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Rather than describing what you expect from each sensor option, it would be better to specify exactly what you want to measure/detect; For example, it was not clear if you just want to detect the presence of water, or the depth of filling as well
...Water is an insulator not a conductor..
What does this mean?I would need to design an underwater electrode (no salty water, only fresh) that would produce voltage changes in the order of mV (1-20 mV). It does not really matter if the changes are positive or negative, however it could be nice to be able to control their sign.
I still don't understand how you want to produce the 1..20mV with the use if a LED. Read a LED's datasheet. You will find no voltage value in this range.I though one way could be to use LEDs as when they light ON they cause a drop in the circuit voltage of some few mV (1-5 I guess).
In the marine environment they use silicon bronze or stainless steel for underwater hardware because they don't erode easily with electrolysis. The best stainless for propeller shafts is Aquamet 22. https://www.aquamet.com/aquamet22.nxg
If you can find an old propeller shaft at a marina that is not eroded, it is probably Aquamet 22. It should conduct easily for your electrodes.
Hi,
What does this mean?
Does it mean you want to control the magnitude of voltage of each segment from 1mV to 20mV? --> you need to give the resolution / granularity?
Klaus
Or has every segment a predefined voltage and you just want to switch it "ON"? --> then you need to say what the "OFF" state means: is it "high impedance" or is it tied to 0V?
I still don't understand how you want to produce the 1..20mV with the use if a LED. Read a LED's datasheet. You will find no voltage value in this range.
Klaus
cutting a steel rod in thin "chips"
I don't know how easy is to find someone cutting a steel rod in thin "chips" but...
As far as I understand, this is a behavioral physiology experiment setup...
As far as I understand, this is a behavioral physiology experiment setup. Reviewing the thread, I get the impression that at least half of the contributions aren't understanding the context and respectively make misleading suggestions. Surely I don't apply to asses it in detail.
I believe, a better idea is to get in contact with a scientist at your site who masters both physiology and electronics (also electrochemistry) and discuss the experiment details.
One fact to be considered is that each animal, sensor setup, and each reservoir layout will give you a different set of information, and the work now goes into the field of data mining, which is a rather inferential 'science', ie you should try extract through different mathematical experiments how could group such patterns. In this case, there is no single solution, each raw data calls for a different approach; BTW, instead of measuring the electric field, I would recommend considering the magnetic field, and standardizing a salinity and temperature for water, in order to avoid discrepancies.The "electrical pattern" would be then used in experiments in which live animals will navigate the "electric field", field that can be changed via software depending on the need. The animal behavior would be videorecorded and that is why I thought perhaps using LEDs could be actually interes
As far as I understand, this is a behavioral physiology experiment setup. Reviewing the thread, I get the impression that at least half of the contributions aren't understanding the context and respectively make misleading suggestions. Surely I don't apply to asses it in detail.
I believe, a better idea is to get in contact with a scientist at your site who masters both physiology and electronics (also electrochemistry) and discuss the experiment details.
For this to be a science project there needs to be some scientific input and output still missing from Livio.
In Ireland...
The electrical conductivity of Irish waters varies from place to place; the usual range in value is 45 micromhos per centimetre in acid waters and 300 micromhos per centimetre in the alkaline limestone waters.
They use it for diverting trout and Eels away from dam turbines, or towards fish counters or for improved fishing.
These types of experiments have been done for almost 90 years.
When pulsed at 30 pps from a relay coil and 12V truck battery generates 350V with a pulse duration depending on above conductance and L/R ratio where 100 micromhos are now called 100 microsiemens (uS) which =1/R means 10kohms but the capacitance on the length wire is far more significant on pulses and can be as low as 100 ohms reactive impedance.
They properties hold true also for detecting E fields.
Livio said "water is a solution containing ions and charged molecules"
Yes conductivity changes in typical lakes depending on pH level to support synapse propagation biology, but pure water is also a highly polar liquid which even when pure has a dielectric constant of 80 meaning is stores and conducts electrical charges 80 times better than air.. The pH offset just makes it more conductive (real resistance not stored charges)
In biology, the dielectric stores a charge when triggered to discharge, propagates in a chain reaction of a stored charge as a pulsed rep rate in the dielectric.
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The human CSF has a very strong negative temperature coefficient on conductivity with 1.79S/m and -2%/'C.