Circuit detectors and sensors based electronics projects

Using this circuit diagram can be designed a very simple liquid detector using common electronic components. The liquid detector may operate an active buzzer, to make a sound when is reached a certain level of water.

This vibration detector motion) is constructed using bipolar transistors and consumes only 0.3 mA in standby.

A very simple electronic thermometer can be designed using electronic diagram below. Thermometer displays temperature radiator not only on two displays, but also provides an output for switching can be used to connect a fan.
This circuit consists of four parts: a reference voltage source IC1, IC4 sensor, IC2 and IC3 the display, the switching IC5.