I want to read the voltage generated in mushrooms.
How would I start on this project. Do I need EEG sensors (and which are the cheapest ones?)
What would be the cheapest/fastest way to achieve this. I do not need high sensorvalue, would be nice.
Thanks!
What range of voltages are you expecting to read ?
How and where will the sensors be connected to the mushrooms ?
No idea of the amount of voltages. I just want to read differences.
I would plug the sensors in the mushrooms directly.
I want to send the data via osc to my RPi.
There was another of these "mushroom voltage" posts on the forum recently. The answers will be the same: use an instrumentation amplifier, or maybe the HX7111.
"osc"?
Probably, after hours of meditation and a short ceremony, in a field. But with an experienced spirit guide present at all times.
There may, of course, be an element of magic too bearing in mind that mushrooms are involved
You will have to get their permission first. How many mushrooms are you going to monitor?
Open Sound Control, it is a protocol used for communication data, not always concerned with music, over various hardware paths. It was originally designed as an IP and has a URL type structure.
I was next to someone exhibiting at the major UK Maker Fair a few years back that was using a laser to detect the sphores from a mushroom to generate audio notes.
Seriously though I think you get much better results using tomato plants. With that you stick two pins in the same stem of the growing plant. They are said to react to "pain and stress "
This is what I'm looking for. Putting two pins in the mushroom and see what happens.
The laser spore thingy also sounds cool.
The load sensor doesn't look like an option? Or am I mistaken?
Why not?
Is the sensitive enough?
YOU need to answer that question.
You have already stated that you don't know what voltages to expect, so do your research.
Before you devote tons of time to designing a measurement system, why not do some experiments with some lab equipment like a DMM?
What you have to be careful about is knowing what is generating the voltage. It could be coming from the mushroom or it could be coming from a chemical reaction between the pins and what they are stuck in.
As an example I was once doing an experiment on sewage to see if I could detect the difference between it and sludge, using brass electrodes. The idea was to measure the resistance between the electrodes, but I found it generated a voltage of about 0.6V. This was due to the reaction between the brass and the sewage.
Use platinum pins, of course.
I would suggest gold. You can get gold plated pins in embroidery shops.
I would spend a little time researching what has already been published.
scholarly article mushroom electrical signals - Google Search
Any project, IMHO, should begin with a trip to the Internet library 
And Google really does care how you pose the inquiry, least your search will be overloaded with junk results.
I don't know anything about this but voltage is "meaningless" without a voltage difference and you are unlikely to get any difference by sticking two probes into the meat of a mushroom.
i.e. If you connect the negatives of two batteries together and you attach your meter probes to the positive terminals, you won't measure any voltage, unless one battery has more charge than the other, and then you'll measure the difference.
You might get something with one probe in the ground (near the mushroom in moist soil for good conductivity) and the other probe in the mushroom.
People make potato batteries and apparently you can get enough energy to light an LED, which I'd say is impressive! But as mentioned above, this is simply a chemical reaction, and dissimilar metals are used as probes/terminals to get a positive & negative terminal.
The Arduino by-itself can read down to about 1mV with the optional 1.1V reference. The 10-bit ADC reads 0-1203, so a reading of 1023 equates to 1.1V and a reading of 1 is about 0.001V. You'll need a high-resistance pull-down resistor (maybe 10M) to keep the ADC input from floating-up. A plant isn't going to put-out much current so you need a high-resistance load or the voltage will drop.
To measure lower voltages you'll need an amplifier.
Likely a medical doctor once said the same in the dark ages before the development of EEG.
Personally, I have no idea what the results would be, it seems to me to be a bit of a strange experiment, but from my earlier reference, there seems to be some science behind such investigations.
Yes ... But that is for DC. One would suspect that the AC component "might" be different over time.