Digital code lock
Description.
This is a simple but effective code lock circuit that has an automatic reset facility. The circuit is made around the dual flip-flop IC CD4013.Two CD 4013 ICs are used here. Push button switches are used for entering the code number. One side of all the push button switches are connected to +12V DC. The remaining end of push buttons 2,3,6,8 is connected to clock input pins of the filp-flops. The remaining end of other push button switches are shorted and connected to the set pin of the filp-flops.
The relay coil will be activated only if the code is entered in correct sequence and if there is any variation, the lock will be resetted. Here is correct code is 2368.When you press 2 the first flip flop(IC1a) will be triggered and the value at the data in (pin9) will be transferred to the Q output (pin13).Since pin 9 is grounded the value is “0” and so the pin 13 becomes low. For the subsequent pressing of the remaining code digits in the correct sequence the “0” will reach the Q output (pin1) of the last flip flop (IC2b).This makes the transistor ON and the relay is energised.The automatic reset facility is achieved by the resistor R11 and capacitor C2.The positive end of capacitor C2 is connected to the set pin of the filp-flops.When the transistor is switched ON, the capacitor C2 begins to charge and when the voltage across it becomes sufficient the flip-flops are resetted. This makes the lock open for a fixed amount of time and then it locks automatically. The time delay can be adjusted by varying the values of R11 and C2.
Circuit diagram with Parts list.
Notes.
- Assemble the circuit on a good quality PCB.
- The circuit can be powered from 12V DC.
- Mount the ICs on holders.
- The L1 can be a 12V, 200 Ohm SPDT relay.
- Capacitor C1 should be tantalum type.
- The C1 and C2 must be rated at least 25V.
sir, can plz anyone tell me d way v can change d code? n plz, tell me for wat kind of locks v can use it?
Can we change the code in this circuit sir..?
that was a typo error from my part. i have corrected the circuit
thanks for pointing the error
Admin
Pin 9 should not be grounded, it is a mistake. Gentleman who made this drawing was too much excited and in a hurry to share so he left two mistakes in the schematic for people to wonder. Never mindm search the pin configuration on the net and use only IC CD4013 (not CD4049). Cheers….
pls if dere isn’t a grounded pin 9 in ic1a which pin is den grounded, and wld it be at d relay that there wld be an output after entering the code or pushing d right buttons
Hi Chianmy sorry it was on the same frame this circuit was drawn so please leave those words CD4049 use CD4013 instead.
Why is it mentioned as ‘Digtal code lock using CD4049′ below the circuit diagram?
please can you upload the breadboard connection for this circuit
Hi Ilija you are correct IC1 pin no9 shown as going to ground is wrong. delete that line other wise the circuit is correct.
yes, what does it mean pin 9 ?!? I don’t understand it
Can you please tell me what will happen when the relay is energised? Where do you put the motor? Thanks!!
HELLO GREAT CIRCUIT HOW EVER THE FIRST IC IC1A HAS TWO PINS 9 LISTED IS THAT AN ERROR CAN YOU PLEASE CONFIRM
THANKS
Thank u sir,i am fully impressed by getting this topic.&soved my doubts.
plz give its state diagram to understand its working….plz plz …i have just 2 hrs to submit this project and perform in viva
sory i want to ask again,, i have been made it, but why it doesn’t work?? i gave it suplay 12 v and i use relay hrs4h and connect it to DC motor,, but the DC motor doesn’t work..
Hi Naufan L1 can be the solenod coil of the latch or through this relay’s contact you can operate the locks solenoid.
excuse me,, i want to ask what is the function ogf the relay coil??
Hi Sir. how can i change the code if i want to change it beside changing it from the circuit’s wire? thank you.
I appreciate this entry. This was super cool.
kindly give me materials 4 the digital code lock
it is a very good projects but there is not information of realy and how to control motor.you have to use your mind to control the motor.
Thanking you for giving the code lock circuit.
By this my problem is solved. Thanking you once more