This project is very simple and electronic lock of good quality.  The lock can be opened only by pressing the push button according to the code.  You can use this lock for locking or unlocking of your car, jeep and computer etc. The main attraction of this project is that in case the push buttons are not pressed in sequence then pressing wrong push button will reset and make un active the properly pressed push buttons.




In the progressive modern age the thieves are also become progressive.  The old technique of lock system does not stand before the thieves of modern age.  Modern electric locks are developed which are proving more useful.  You can utilize this project with greater confidence.


Two Flip-Flops IC1 and IC2 [CD4013] are used in the circuit.  Total four push switches are connected in series with positive supply from pin no. 3 and 11 of both ICs.  In circuit diagram the wires to both end of these switches from both ICs [3, 4] are termed W, X, Y, Z terminals respectively.  When the switches are pressed in this order the relay in circuit will be activated.  In other words lock will be opened.  Ten push switches are connected in the circuit which are marked from 0 to 9 numbers.  In this project for example code 2051 is taken.  Thus 2 is connected with W, 0 with X, 5 with Y and 1 with Z.  Besides this rest of switches 3, 4, 6, 7, 8 and 9 are connected with reset terminal.  This reset terminal is connected with pin no. 6 and of both IC.  Rest of the 6 push switches reset the Flip-Flops.  The pin no. 14 of IC1, IC2 are connected with positive and pin no. 13 of IC1 is connected with the pin no. 5 of IC2.  Whereas Pin no. 5 of IC1 is grounded.  When the switches are pushed to proper order then the output from the pin no. 13 of IC2 goes to the base of Q1 [BC557].  The amplified signal from the collector of the transistor operates the relay.  Thus the car is started from relay.




  1. Use IC base for the IC.
  2. Take care that there is no shorting on PCB while soldering the components.
  3. Check all the components so that components are OK.
  4. Take care of cathode and anode terminals of diode while soldering.
  5. Use good quality presets.
  6. Solder the C,B,E terminals of transistor carefully.