Magnet switch and smart card reader

[Xenobius]

Hello people, I would kindly like to ask somthing which is giving me a lot of trouble finding on the web.

I am trying to make a small cupboard with strange methods of opening it!!

I was thinking about making somthing from inside the wooden door at a random place only known by me, and when I put some sort of magnet from outside, the sensor from inside would sense the magnetism and give a logic 1 (5v). Than I would insert a smart card in a slot and if verified OK, would give me another logic 1 (5v).

Than with the help of an AND-GATE, I would have 2 logic 1 and an input and the AND-GATE would give a logic 1 switching a transistor and the transistor switching a relay which would give supply on an electric lock and the door would open.

The third problem is about the AND-GATE because as soon as I remove the magnets the logic would go to 0 (0v) and I would not have enough time to open the door.

SUMMERY: I was thinking of making 2 of these magnetic sensors and 1 smart card reader. I would kindly like to ask somone to help me with the megnatic sensor, the smart card circuit to read a smart card and a person to write me a code so that the TIMING could be adjusted so that I would have 4 seconds chance to put all 3 sensors into logic 1. Otherwise it would reset and I have to start again. And give me 4 seconds chance to OPEN the door. Once the door is open, the pic would reset and the electronic lock would close, so that when I am finished from putting stuff inside the cupboard, I just close the door and everything would be closed and reset and would need me to input the 3 logics AGAIN if I need to open the door.

THANKS EVERYONE for the help. I really appriciate and am looking forward to put up a PDF file of the WHOLE finished thing when it is done!!

THANKS AGAIN

[japroach]

"The third problem is about the AND-GATE because as soon as I remove the magnets the logic would go to 0 (0v) and I would not have enough time to open the door."

flip-flop that is reset when the door is opened. Or it can be reset once your timer has timed out (count-down is activated by the smart card).