Introduction: Electronic Combination Lock

About: i am really intrested in electronics.

Here i will show you how to make a password lock. This is just a fun project, please don`t use this to make your house secure.

Step 1: Hardware

4001 ic

4081 ic

4 slide switches (must have 3 pins)


2.2k resistor

3v power supply



Step 2: Connections

Connect the first leg to negative rail, third leg to positive rail.

Do this for all 4 switches.

Second leg of first switch to pin 1 of 4081 (not 4001)

Second leg of third switch to pin 2 of 4081 (not 4001)

Pin 3 of 4081(not 4001) to pin 5 of 4081 (not 4001)

second leg of second switch to pin 2 of 4001 (not 4081)

second leg of fourth switch to pin 1 of 4001 (not 4081)

Pin 6 of 4081(not 4001) to pin 3 of 4001 (not 4081)

Pin 3 of 4081(not 4001) to pin 13 of 4081 (not 4001)

Pin 4 of 4081(not 4001) to pin 12 of 4081 (not 4001)

Anode of LED (the long wire) to pin 11 of 4081 (not 4001)

Cathode of LED (the short wire) to the negative rail via 2.2 k resistor

Negative of battery to negative rail, positive of battery to positive rail

Step 3: Done!

The passcode for this lock is ON OFF ON OFF. As I said don`t attach this to your door and use it as a real security system, even if you relocate to a perf board.