Hi Nicolas
Great , just the result we want
its just a matter of having the probe pulling the input in the opposite direction to
the on board pullup / pull down resistor
(not always easy see if you spend too long looking with out a break )
the resistors maximum voltage is not going to be an issue since the circuit only has a 5V supply
using a 1/4 watt resistor any thing from 120 ohms to 1000 ohms will be OK
with 1/8 watt resistors use 270 ohms to 1000 ohm resistors
(the values are high enough not to run the resistors at the maximum wattage
I aim for 70 to 80 % of the maximum )
if your local store is like the Tandy ( Radio Shack) stores that used to be in the UK
then 1/4 W resistors like this will be OK -
E3 Series 480 piece carbon film resistor kit | Rapid Online
or 1/8 W resistors like this :-
Not Found | Rapid Online
the 36 ohm 10 watt resistor you are using should ony be warm if the probe is permanently in contact
with the touch plate
( 5/36 ) X 5 = 0.69 W
which is only 6.9% of its maximum (10W)
John