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Combination Lock Kit image Zoom

Combination Lock Kit

Uses two 14013 quad D flip flops. Set you own secret 4 digit code.
Any wrong number or wrong key-in sequence resets the lock. Separate touchpad PCB, 3' cable, connectors & 12V relay
included. Excellent introduction to security devices.

Availability: In stock
Assembly Required: Yes



Assembly Required!
Product Description


    This kit gives a cheap, easily understandable, and adaptable combination lock.ᅠ The relay will only respond to the right sequence of four numbers keyed in on the remote keypad.ᅠ Touching any other key will reset the lock.ᅠ The key combination can be easily changed on the main mother board.

    The kit is constructed on a single-sided printed circuit board (PCB).

    Choose four numbers you want to be the secret combination.ᅠ The numbers must be different.ᅠ Let us choose 1357.ᅠ That is, we want to touch 1 then 3 then 5 then 7 on the Remote Keypad for the relay to trigger.ᅠ Touching any other number we want to reset the unit.

    On the main PCB connect Pad A to one of the pads on line 1 using some of the hookup wire provided.ᅠ Connect pad B to a pad on line 3, pad C to a pad on 5, pad D to a pad on line 7.ᅠ Now connect the five remaining numbers to the five pads on the RESET pad.

    Connect a 9 to 12V power supply.ᅠ The combination lock is now ready.

    A 12V relay has been provided with the kit.ᅠ It can switch a main powered device such as a light.ᅠ The 14013 dual D flip-flop (FF).ᅠ Each 14013 contains two D flip-flops.ᅠ The four FF are connected to A, B, C and D pads.ᅠ ABCD gives the 4 digits which must be keyed in in sequence for the relay to trigger.ᅠ The five remaining digits may be connected to the RESET PAD.ᅠ If one of these digits is keyed in during the ABCD sequence then the circuit will reset.

    The ABCD touch pads are connected to the clock input pins 3 and 11 of each 14013. ᅠ ABCD pads are normally tied low by the 4M7 resistors.ᅠ Touching the pads of each keypad briefly pulls the input high and the state of the FF is altered.ᅠ The output Q pins (1 and 13) are wired so that when the correct sequence is keyed in then pin 13 of IC2 turns on the transistor.

    The reset keys are all wired to the set pins (6 and 8) of each IC.

Additional Information

    Additional Information

    SKU QK29
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