Tuesday, April 19, 2011

Minecraft Circuits: Programmable Digital Keypad Door Lock

An example of a fully programmable keypad lock for a door in Minecraft. There are eight buttons with an order-specific, repeatable, four-digit sequence. The advantage of this circuit design is that I can change the order of the digits however I want without hardwiring any part of the circuit. Overall, this took me around 3-4 days to finish. Compared to my sequential combination lock (see channel), this was definitely a more complex project. Features: * Eight push buttons. * Four digit sequences are used. * Back-to-back repetition is allowed. * Password is easily changeable but obscure. * No hardwiring; fully programmable. * Reset switch and circuit. Total possible permutations with 8 inputs and a 4 digit code: n^r = 8^4 = 4096 combinations. In other words, you could enter 4096 different combinations before arriving at one that is valid. Adding more digits to the sequence is easy with the circuit design, but I felt that this was plenty. Future additions: * Permanent lock feature after X failures until a certain amount of time has passed. * Trap doors (involving cacti, water, lava, and/or mob spawners). * Automatic reset (simple pressure plate or clock generator). * Randomly generated password. How it works: A multiplexer is connected to a decoder which feeds the password one digit at a time from a counter if the input is correct. Otherwise, the circuit is reset. I'm using OR gates to compare input to the output from the decoder to determine the mux's output. Any questions ...


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