alarm systems

A programmable code lock can be used for numerous applications in which access to an article/gadget is to be restricted to a limited number of persons. Here is yet another circuit of a code lock employing mainly the CMOS ICs and thumbwheel switches (TWS) besides a few other components. It is rugged and capable of [...]

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 [...]

This is my electronic combination lock to use with an outdoor gate. The functionality is implemented in software. It turns on a relay (usually to open a door) for a few seconds if someone enters the valid code. Alternatively, it works as an ON/OFF switch, which toggles the relay each time the code is entered. [...]