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Water sensors/detectors

Former Member
I'm trying to build a model electronic car which would operate using a PIC chip. I want to have a feature which would allow it to detect water spills in the floor and ring a buzzer.
Basically, the car will move around the room and it should be able to detect any form of liquid spilt. What types of sensors do you have for this purpose? May be I can attach/paste something to a wheel of the car?
  • A very simple way to do this is to simply have two wires drag along the floor. The ends dragging on the floor should be stripped of insulation. One of these wires should be connected to the base of an NPN transistor that has the emitter at the car's common or ground and the other wire should be donnedted to the power source (battery) through a resistor (anywhere between 1k and 47k should be fine). The collector of the transistor is connected to the battery through a resistor of 10k to 47k.

    When there is moisture on the floor, that moisture would conduct base current to the transistor, turning it on. The collector of the transistor would then go low. The collector can be connected to a port pin of your PIC and a logic low on that pin will indicate the presence of moisture.

    Good luck!