combination lock help

Thread Starter


Joined Aug 3, 2010
I need help regarding your combination lock circuit.

1st question

i've designed this circuit but i want to add some kind of limitation, like after 3 consecutive wrong input the circuit must not allow to input another one and required to be reset but i dont know how to do this ??
I think it can be done through counters but i really dont know how to use counters because i neved studied counters in my college.

2nd question

To give an extra effect i have added a Buzzer in parallel with the RED LED
and used 555 Timer IC for toggling Buzzer and RED LED however the LED is really DIM and the Buzzer sound is really low :( , i know this is happening because the voltage coming in the RED LED is very LOW and i dont know what is the maximum voltage required to light RED LED normally and BUZZER at its maximum noise.