Digital Combination LockCircuit Project Tutorial


Posted on Feb 4, 2014

The circuit above makes use of the CMOS 4017 decade counter IC. Each depression of a switch steps the output through 0 - 9. By coupling the output via an AND gate to the next IC, a predefined code has to be input to create the output. Each PBS switch is debounced by two gates of a CMOS4001 quad 2-input NOR gate. This ensures a clean pulse to the i


Digital Combination LockCircuit Project Tutorial
Click here to download the full size of the above Circuit.

nput of each CMOS 4017 counter. Only when the correct number of presses at PBS A will allow PBS B to become active. This is similar for PBS C and PBS D. At IC4, PBS D must be pressed 7 times. Then PBS C is again pressed 7 times, stepping from output 1 to output 8. The AND gate formed around CMOS4081 then goes high, lighting the LED. The Reset switch can be pressed at any time. Power on reset is provided by the 100n capacitor near the reset switch.




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    Voltage regulator for projection lamp
    600 Watt Mosfet Power Amplifier with PCB Schematic Diagram
    Microphone Condenser Pre Amplifier Circuit
    user-customizable PTT/FSK API of MMTTY
    Stepper
    sound capture
    Battery charging indicator circuit
    Filaments Detection Circuit
    OpenLx USB DMX interface
    Sawtooth generator circuit II



    Top