hi, im trying to set a relay to go off when resistance rises.
the system works when i connect it via usb, but when i try it on 9v the relay wont turn on.. ive debugged it making it switch for 3 secs at the setup stage, and that goes on well, so i guess the problem is with the sensor?
the sensor is just a pair of wires connected to an analog pin and the 5v pin (the analog is grounded with a resistor)
any ideas what could be going wrong?
I would like to see a wiring diagram of how you are hooking every thing up, but at first thought if all is working well with USB power but not with a 9vdc battery then the battery most likely can't supply enough current to operate the relay coil. You could try a 6 cell AA alkaline battery pack and see if the cures the problem. Those small 9vdc batteries are really useless for most Arduino projects, they are just too wimpy with current and are too expensive for the little power they provide.
Lefty
oh nevermind. im a doofus. i was reading the wrong analog pin -_-
mods, plz delete this fail post