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Combinational Lock using shift registers Answered

last year, i made the circuit of this already but now my brother is asking for my help and i cannot remember it now. im focusing right now in programming and forgot my logic circuit skills..please help me to remember this...

what i remembered is that i have shift registers that memorized the buttons (0-9) i pressed...then i enter again a sequence of numbers and the device will check if it corresponds to the numbers i entered...the led will light if it is correct and will not if the numbers entered did not match the default numbers... i still have the list of some materials, 3 universal shift registers, 1 nand ic, 3 xnor ic, 10 toggle switch and 1 hold switch..  its not a very complex circuit..my only problem is to remember on how will i work with the shift registers...

please enlighten me once again



Do you have a logic diagram or schematic? If you need a reference for the shift register you can find it here. http://datasheet.octopart.com/SN74LS164N-Texas-Instruments-datasheet-152359.pdf (I assume you're using serial in/parallel out.)