AndresR145

Hello Olivier,a fascinating setup. I always wanted to do the calibration myself but never found the time to do so.First, the curve you made is quite impressing and mostly symmetrically. I wouldn't expect it to be 100% linear since nothing is perfect. Your e-field plates are just 13cm apart as you said. This isn't much. The dimensions of the field mill itself between the plates will cause the field to become inhomogeneous a d distorted because the plates are not evenly spaced electrically anymore. Furthermore the field vectors might be bent, entering the field mill partially horizontally. This also renders the field inhomogeneous. To get good results the dimensions and distance of the plates should be magnitudes bigger than the dimensions of the field mill. To be honest, the linearity…

Hello Olivier,a fascinating setup. I always wanted to do the calibration myself but never found the time to do so.First, the curve you made is quite impressing and mostly symmetrically. I wouldn't expect it to be 100% linear since nothing is perfect. Your e-field plates are just 13cm apart as you said. This isn't much. The dimensions of the field mill itself between the plates will cause the field to become inhomogeneous a d distorted because the plates are not evenly spaced electrically anymore. Furthermore the field vectors might be bent, entering the field mill partially horizontally. This also renders the field inhomogeneous. To get good results the dimensions and distance of the plates should be magnitudes bigger than the dimensions of the field mill. To be honest, the linearity of your curve is going beyond my expectations!!!The 47mV offset is weird since you have no amplifier. Is this offset always present or only while the disk is rotating? Check if the offset maybe comes from the multimeter. Another source could be ac hum interference that is asymmetrically. Do you have the same offset at a different location or even outside? Now the polarity issue. The positive electrode of a voltage source means it is a source of electrons. Electrons are negative charge carriers. They generate a field that repels the electrons in your disk segments. Thus the disk and your capacitor are facing a loss of electrons. For your multimeter this is a negative voltage. Reverse the field and electrons coming from ground will be attracted and will gather on your disk and capacitor. In this case your multimeter will tell you it's positive because of the excess of electrons. This is the usual confusion between technical and physical polarities.

Dont't hurry and good luck for your surgery. Recover well!

Hello Oliver. I already thought about building the field mill in plexiglas myself. Triboelectric charges can definitely be a problem but as long as you don't run it with clothes I think this is not an issue. Charges only build up on friction with clothes. If you leave the mill untouched the charges will be drained fast by the humidity of the air I think. I don't think triboelectric charges will build up when the motor is running since plexiglas is moving against plexiglas. The same argument accounts for an enclosing. Especially outside, wind, dust and humidity will drain triboelectric charges quickly.

Hi Olivier,thank you so much for your feedback! Resopal is s good idea since it is well available and yes the shield plate is crucial. I think it's size and position are still open to improvement. Since some people contacted me and asking me to manufacture field mills for them i am planning to make a very simple version made out of cardboard. This material can be strong and you can cut it with good scissors or a knife.By the way, an output of 300mV without amplification in your underground lab is an impressive result!I hope more people will replicate the mill and maybe start a network of hobbyist e-field monitoring stations.Good luck and greetings to Switzerland!

I really appreciate if someones shares The same fascination for this phenomenon. Thank you!

This is correct. In my experiments i made the assumption that the electric flux is vertically oriented and in fact i never observed horizontal field components giving me a signal. Of course the current design would be susceptible to field components with spatial orientations between horizontal and vertical principally. To be sure you'd need to enclose the sides with shields as you described. For our purposes, i don't think this is necessary but if you do you should take care to keep at least the same distance between those new shields and the disk as it is now between disk and the upper shield. Otherwise the voltage gain by the capacitor effect would be negatively affected.

Hello my friend and thanks for your kind comments. I really appreciate your plans on doing researches on the variations of earths electric field in thunderstorm. This is a startling project and really of the kind i wanted to fuel with my design! Now i come down to your questions.1) Every Motor will work that is supposed to run on a more or less constant speed. But even this requirement may be weak. I have the theory that, depending on the setup (disk size, charge collector capacitor, input current on OP-AMP) we need a minimum rpm of the motor but from a certain rpm on upwards there would be no influence of the collected charge anymore. But as long as this is theory just choose any motor with stabilized rpm you like.2) I first was very concerned about the quality of this capacitor and i t…

Hello my friend and thanks for your kind comments. I really appreciate your plans on doing researches on the variations of earths electric field in thunderstorm. This is a startling project and really of the kind i wanted to fuel with my design! Now i come down to your questions.1) Every Motor will work that is supposed to run on a more or less constant speed. But even this requirement may be weak. I have the theory that, depending on the setup (disk size, charge collector capacitor, input current on OP-AMP) we need a minimum rpm of the motor but from a certain rpm on upwards there would be no influence of the collected charge anymore. But as long as this is theory just choose any motor with stabilized rpm you like.2) I first was very concerned about the quality of this capacitor and i thought it must have as less leakage current as reasonably possible. This was due to my experiences with electrostatic machines where you tediously and carefully have to collect charge carriers in a leyden jar until you gain enough of them to realize a fulminant discharge. Those setups don't forgive you the slightest design flaws that yield into leakage current. Now, here in this design my experience is that this is not that dramatic. We don't reach high voltages and this is where the leakages become nasty. So i would say you could use any capacitor apart from electrolytic ones. We have a steady stream of incoming energized charges and we always have some unavoidable leakage anyway. At least the OP-AMP swallows some nanoamperes.3) Generally there is no tolerance and you can make it the size you want. You just have to obey two simple rules. The smaller the capacitor is the faster it will charge-up but the "averaging" effect for interference and the the discharge from leakage currents will have more and more impact on the signal. Think of the capacitor as a part of a lowpass. The higher you make it the more your signal becomes a steady DC. If it is too small the signal becomes noisy. This leads us directly ti the second rule. The bigger the capacitor is, the better becomes you signal quality but the time to charge the capacitor also increases. At some point perhaps you would need to increase the time between motor start and taking the value from the capacitor.4) I used this from amazon: https://www.amazon.de/gp/product/B009L9EWPU/ref=pp...But you also can try different materials. Sometimes electronic components are delivered in some kind of "electric foam" to protect the against ESD. Also the small bags where the components are wrapped-up are made of plastic that has a conductible surface. You can take everything that is smooth and a little conductive. A high impedance is nor problem because we are working with very tiny currents. But you should avoid using metal whiskers. I tried copper and steel and they where ruining the plates.

This is simple. Use the command "setintervall <value>" to change the sample interval as you wish in seconds. E.g enter "setintervall 60" for setting the sample interval to 1 minute. The value can be between 10 and 3600.

Hello again! That really strange. May i ask what RTC-module you are using? Do you have the the CR2032 backup battery inserted in the RTC-module?

Hello! Sure, the RTC is an I2C coupled module available as the standard Arduino RTC shield. It runs on an DS3231 clock chip.

As always the most simple approach is the best one. Great work!

No, this is just an ordinary potentiometer to be trimmed with a screwdriver.

Ah ok, this is the potentiometer R5(22K).

Hi! Sorry but i don't know about what element you're talking about. Where is the black and red element you mentioned? Is it on one of the pictures, the schematic or the video?

A red and black element? You mean on one of the pictures, the video or are you refering the schematic?

An awesom and somehow crazy idea! I really love it. Good way to ruggedize your smartphone.

Thank you so much for your comments. I loved to fuel your imagination!

An incredible great work!

An excellent question! My first intention of using a stabilized rpm was that everything you do not understand properly has an impact on your setup. So i made it this way to be safe. Later i thought deeper about this issue. Generally the disk-segments are rendering a current flowing into the charge collecting capacitor. The faster you turn the disk the more current flows. On the site of the charge collector you have an unavoidable leakage current because your capacitor isn't ideal and the electronic amplifier always has some input current. So the first finding is that the current from the segment disks must be larger than the leakage current. You need a minimum rpm. The second question is what happens if we exceed this minimum rpm more or less? Obviously he charge collector will charge mor…

An excellent question! My first intention of using a stabilized rpm was that everything you do not understand properly has an impact on your setup. So i made it this way to be safe. Later i thought deeper about this issue. Generally the disk-segments are rendering a current flowing into the charge collecting capacitor. The faster you turn the disk the more current flows. On the site of the charge collector you have an unavoidable leakage current because your capacitor isn't ideal and the electronic amplifier always has some input current. So the first finding is that the current from the segment disks must be larger than the leakage current. You need a minimum rpm. The second question is what happens if we exceed this minimum rpm more or less? Obviously he charge collector will charge more or less quickly but up to what limit? Well, the upper limit is specified by the fact that every disc segment is a capacitor by itself. It takes some charge and generates a field against ground. By dragging the segment away from the grounded plate the energy of this charge gets amplified resulting in a voltage. When the segment gets in contact with the charge collector it takes this charge up to it's voltage. That means the voltage on the charge collecting capacitor can't get higher than the voltage of the segment. The conclusion is that we need some minimum rpm. Above it an increase of the rpm only results in a faster charging of the charge collecting capacitor but it doesn't change it's end voltage. So far the theory, it's unproven yet.A calibration is generally necessary because actually we just have digits with no dimension. I'd have to put the device between two large metal plates and apply a voltage to it. So i could calculate the field strength and the field would be more or less homogeneous. Then i could take the digits and calculate the proper transformation factor.

Pretty nice idea!

It's 480 rpm!

Great idea, thanks!

Thanks! I also made the FET charge detector. The problem with this device is that it still takes energy from the field. In my experience it was only needful to detect changes of electric flux but you could not measure a static electric field.

I'll check it and will tell you.

Sorry! Yes I know the article on wikipedia and no, I don't drive or own a Delorean.

Well, no. I don't have connections to the academic world. So there is no publishing. Currently the diagram i showed in my project is the only one. I'm planning to look for a database in the internet that provides weather data suitable to be used in gnuplot and then doing a long term measurement and evaluation and see if there are correlations showing-up. But this is a long runner i have to in my limited free time.

Great! I was always looking for something like this. Fuels my ideas!

A really nice idea and remarkable craftsmanship.

What a great idea and realized very well under heavy time pressure. Excellent!

Thanks for your polite comment! I actually was not earlier but growing old teached me it's lessons

Thanks for your polite comment! I actually was not earlier but growing old teached me it's lessons😏

Nice and accurate instructable. Thank you.

Nice project and you made a really good and understandable documentation. Well done!

Simple and great!!

What a nice idea!

Thank you so much! My mechanical skills are pretty limited but i tried my best.

Thanks you like it!