SIMPLE ELECTRONIC CODE LOCK USING 555 IC

In this project we can operate the operation of locking or unlocking it is just a dummy project it does not lock or unlock any thing it just operates some electronic action when switches of correct number are pressed.
Here we are using six switches ( you can add more) in which 3 are CORRECT SWITCH and 3 are WRONG SWITCHES only right combination of CORRECT SWITCHES unlocks the circuit.
In the circuit 555 timer IC is used in bistable mode , which can be reset or triggered by applying a low input on the corresponding pin. The CORRECT SWITCHES are connected to trigger pin( PIN2) when all the switches are pressed trigger pin receives a low input and the LED glows which means the circuit is unlocked. But in case any WRONG SWITCH connected in parallel and connected to reset pin(PIN4) is pressed the circuit gets reset and LED does not blink means circuit is not unlocked so a correct switch combination can only unlock the circuit. In this circuit the circuit unlocks only when S1, S2, S3 are pressed and unlocks if any of S4,S6,S5 is pressed .For operating any AC appliance u can use relay also.

COMPONENT REQUIRED

R1-R2          RESISTORS(100K)


R3                RESISTOR(1M)


R4                RESISTOR(330R)


C1,C2           CAPACITOR(1nF)


S1-S6           SPST SWITCHES


D1                 LED( YOUR FAVOURITE COLOUR..;))


U1                 IC555