I have two seperate metal plates and both have a wire attached. How can I make a circuit, when both plates are touched by 2 people and if they take hands together (or even a third persons is in between) only then arduino activates for example LED.
At first I thought this is would be simple as button circuit, where you have to check only for the connection, but this works only if the plates are beeing connected each other with a wire but if touch one plate with one hand and other with the other, then nothing happens. I assume thats is of big resistance that my body creates.
How could I achieve this? Thank you.
P.S.
I attached little drawing that may help understand my idea.
You need to use a pull up R (say 47k) to the 5v connected to the analogue pin then use the plates as described.
The hands form the other side of a voltage divider. Read the analogue and trigger on a value that you get when the hands are touching the plates.
Weedpharma
Edit, this is not a capacitive sensor! It is resistive.
Could this be achieved without analog pins only with digital?
4rudino:
Could this be achieved without analog pins only with digital?
Yes but it will not be as sensitive.
What is wrong with using the analogue pins?
You have to detect a possibly very low current, flowing from one plate to the other. In addition the wires and persons act as an antenna, catching whatever electrical noise from the ambient. That may require some additional circuitry, to suppress noise and amplify the low current. That circuitry then can detect a certain current threshold and produce a digital signal. Also take care that ESD cannot damage that amplifier.
I noticed in your schematic that the cats were wearing gloves. if these are not conductive, it would effect the readings.
I did not notice that! Maybe then the sensor could be capacitive.
Weedpharma
