Touch Switch Project
Thief’s are attracted to expensive things when they come in our houses. We can protect our product or thing by making them touch proof or we can stop any unidentified persons entry in our house by making door and window touch proof. This circuit alert us when anyone come to stole products from our house or touch any metallic thing at door / window or in side . We can use this circuit to protect our car or bike by making them touch proof.
as we have describe above this product give alarm when any human body touch any of the metallic thing which are protected by this circuit. This project is working on two transistors which make complimentary pair direct coupled amplifier. This circuit basically is a audio oscillator. For oscillation we use collector of transistor bc558 which is connected to the base of transistor BC548 via resistance 10 k and 0.01 or .02 mfd capacitor . Transistor BC-548 is working as a current amplifier and feedback receiver.
When any human body touch the touch sensor which is connected to base of transistor BC548. This transistor conduct with human skin conductance. When transistor bc-548 start conducting it’s forced to transistor BC558 to start conducting. So we get alarm sound from speaker. When we take back our hand then does not connected to base of transistor bc-548 . So it’s does not conduct we do not get the alarm sound.
Same Circuit can be use as Touch Alarm, Water Level Indicator, Rain Alarm etc.
Circuit Diagram of Touch Switch / Touch Alarm / Rain Alarm