Advanced Sequential input code lock
123
456
789
*0#
3589 is the code that is punched in in sequence controlled by a push register.
But 3599 and a few other combinations will work as well cause a 9 =8+1 and so the signal is on Hi. More gates are necessary to sort this out. But sorry, ain't got no more space.
You can chance the code by rearranging the AND gate connections to the counter IC.
You see an ordinary number pad, 4 units of counters, an OR gate decoder dec to bin and four 7-segment displays for a 4 digit code.
The AND gates check if every unit match the right number and turns off the red LED and lights up the green LED.
Always press the LOAD button to finish one entry.
In future a timed square wave generator or a 555 shall take on this task...
Managed...it's all done...Although running low on space...
Enjoy
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