Circuit detectors and sensors based electronics projects

A very simple liquid detector can be built using electronic diagram below. The liquid detector is a detector with liquid alternating voltage and can be built using some very simple electronic components. Voltage alternative for this circuit is made using a gate with Schmit trigger function, which works as an alternative power oscillator.

A simple humidity detector can be built using electronic diagram below. Electronic humidity detector scheme is very simple and uses fewer components can be used for activation of electronic devices when the detector senses a certain humidity.
The sensor is constructed from two pieces of copper placed at a short distance of each other. when the electrical resistance of copper conductors drops below a certain value, Schmit trigger built using transistors T1 and T2 switch. Bistable multi-vibrator is flip through C1, so that at point B there is a low voltage (relay triggers).

A touch switch sensor electronic project can be designed using this simple electronic diagram below. This touch switch sensor use one sense switch that allows shareholders "on / off". The capacitor C1 stores the switching state at the time. Depending on the signal output of gate N1, capacitor C1 is loaded or unloaded. On reaching the sensor, the signal is returned to the entrance of N1, so that switching state change occurs .