I'm somewhat new to Arduino and i need some help from someone who is more experienced than me, maybe a written code or even a way to start because I'm a little lost.
I want to start a project with an Arduino Uno that continuesly measures resistance between a material and sends a signal to a small speaker and LED to blink and beep when the resistance is less than 30 Ohms, i have very little knowledge in programmatic boards and i don't know where or how to start, i have made some simple stepper motor programs before but that's it.
Consider the basics.
You need a reference to compare your readings with.
A micro doesn’t measure resistance, it can only identify states (on/off) or voltages with the ADC
Read up on ohms law - resistance can be derived from a known voltage and the current that flows across it.
Thank you everyone for replying, let me clear up some things, this is a personal project, I'm trying to measure resistance of a very small air gap at room temp and dry air, i tried it with a multimeter and it works, i don't remember the exact measurements but at about 5 microns the resistance was about 500 Ohms, but at about 1 micron or less it reaches about 20 ohms, when touching it reads 0 Ohms on the multimeter, the thing is that i don't want to use a multimeter everytime, i want a simple device that measures the resistance just like the multimeter but beeps when it reaches less than 30 Ohms which tells me I'm about 1 micron or less from touching.
My project here (measures soil resistance) would be a good starting point.
However you havent said what the dimensions of your surfaces are, so you would need to consider the capacitance http://hyperphysics.phy-astr.gsu.edu/hbase/electric/pplate.html
and static electric charges may also affect your results.
So if you use my circuit I'd suggest connecting a suitable resistor (maybe around 10k) between the probes.
How do you ensure the humidity is constant and the air is dust free?
Thank you so much, the humidity isn't very constant, it is a closed environment tho, humidity is always 30% to 40%, for me it doesn't matter that much since the actual goal
is to know the moment the two surfaces are touching (0 resistance) and when it is about to touch, the machine can move in 1 micron steps, 10 micron tolerance is enough for me.