This simple touch switch using the transistor is the touch switch updates from the original version. That the use of IC to control the operation causes difficult for the beginner of electronics. So this circuit is believed to be suitable because it uses TR purely. When it broke also a simple repair. And more profitable team. But the application is easy, that is, when we want to relay connected A and B contract. But when we want to retransmit the release We also play on B and C.
The operating principle
When we touch point A and B there will be some current from point B through our finger to point A. What basis of TR2 this current will make TR2 drive current between pin C and E. This current will pass R-820 Ohms in TR3 pin B causes TR3 to drive current as well.
Figure 1 The cheap touch-switching circuit using a transistor
And this current will pass from pin BE of TR4. When TR4 has current flow through pin E-B, it will also do so between pin E-C. Thus the relay thus derived the current and there is an LED glow to indicate that we know once that the relay is operating now.
While on pin C of TR4 will have almost equal voltage this same point of voltage that through R 4.7M to pin B of TR2 will cause the current flow continuously even release the point of contact. The relay will remain active. When we want the relay to stop working. We also touch points B and C. Some current will flow through our fingers from point B to point C.
And go to pin B of TR1, cause the TR1 line, therefore the current passes through an R-4.7M instead of the pin B of TR2, returned to the ground through pin CE of TR1, Making TR2, TR3, TR4 not conducting current. Drive the relay to separate the contact. Until the touches point new AB.
The system is a simple and reliable tactile security system activated and uses sensor technology to revolutionize living standards. The system provides a better solution to most of the problems that homeowners face in their daily lives. Due to its simple electronic components nature, it is more adaptable and cost effective. The system is divided into three units; The power unit that uses both the DC battery and mains to ensure constant power to the circuit, the trip unit that is responsible for activating the alarm unit and designed to have a lot of time and period and a moderate sensitivity to reduce The false alarm rate and the alarm amplitude unit whose main function is to produce amplitude alarm sound when triggered by the trigger unit in order to produce a large audible sound that can alert the whole neighbourhood or frighten a intruder. The design of the system was achieved considering some factors such as economy, availability of research components and materials, efficiency, compatibility and portability and also durability in the design process. The performance of the system after the test meets the design specifications. This system works on the principle of the touch sensor. The overall system performance and performance depends on the presence of an intruder entering through the door and touching any part of the door. The general system was built and tested and works perfectly.