Smartcard controlled Lock with Relay

Posted on Jul 26, 2012

This design uses a smart card to enable a relay. A Nutchip recognizes its mating smart card among thousand similar ones, because you choose the code to be programmed in the card's memory. No speacilized knowledge is necessary, as we supply the card program and codes. Nutchip truth table is simple as well, so you should be able to adapt it to your needs (e.g., adding more than one card, or timing the relay). Even in its actual form, the board is ready to work in many useful applications: open gates e.g. for park lots. access control to gyms, swimming pools, tennis play fields. switch on central heating or showers, or the football field lights. enable TV viewing, photocopyng, faxing, coffe machine use, telephones etc.

Smartcard controlled Lock with Relay
Click here to download the full size of the above Circuit.

Smartcards are very handy as they are compact, lightweight, and require no batteries. Cards are tough compared to remote controls, are resistant to dirt and wet, and don't break apart falling from a tabletop. If a card gets lost or stolen, you can reprogram the Nutchip in minutes, discarding the old code in favour of a new one, therefore making the old card useless. This card-activated realy requires just an handful of parts and is very simple. The active components in addition to the Nutchip are a 74HC00, a reset generator (IC3) and a transistor for relay switching. Thereset integrated circuit IC3, an MC34064 from Motorola, guarantees a clean Nutchip RESET even in presence of electric noise coming from the power network. Its duty consists of discharging the capacitor C2 as fast as possible when a power drop is detected. But let's introduce the smartcard. We choose a "Funcard Purple": this is the usual name for a card embedding a powerful processor, an Atmel AT90S8515, and a serial EEPROM memory. Other "Funcards" similar to the "Purple" are the "Funcard Prussian" and "Funcard Prussian 256": these should be theoretically compatible, although more expensive. However, please note that we have not tried them, so take our word at your own risk. As the Funcard Purple embeds a microcontroller, you must load it with a program written for this specific task before using it in our circuit. The program is a free download from...

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