A simple and reliable capacitive security card system is designed, fabricated and tested. It consists of capacitive card reader system, an integrator, rectifying circuit, an 8051 microcontroller and LED indicators. Initially rectangular patterns of different lengths are being recognized successfully. The patterns on the security card are scanned with a thin conducting plate, which is the part of the reading system, when card is inserted in the reading system. The variations in the heights of the patterns are being converted into voltages with the help of an integrator. Output of the integrator, after rectification, is converted to digital form and fed to the microcontroller. These data are compared with the data stored in the memory of the microcontroller.
The Proposed System:
The system proposed comprises of a sensible capacitive sensor. Capacitive sensors are widely used in the industry to measure various parameters like position, angular speed, liquid level and pressure. Work on the design of highly reliable capacitive sensors and now these are available in the form of small, reliable, robust and low cost smart sensors are being undertaken.. These drawbacks are overcome by capacitive data system. The hardware for a capacitive card system is generally low in cost, requires fairly low power to operate and provides a non rechargeable memory card .Each card plays their critical role in storing required data for certain entries, besides their high level of data protection. However, there may not be a best card technology for every one. The selection should be made on the basis of the requirements of the individual customer and on the factors such as cost, reliability, ease of use, and environment.