This project provides a good introduction to practical electronics in the form of a "programmable" electronic combination lock. It introduces the builder to a variety of components including the 4013 dual D flip-flop IC.
The Control Board contains the circuitry of the decoding ICs, a number combination matrix for hard-wiring the 4-digit security code (using jumper wire provided) and a relay output for switching an external load.
The Control Board is connected (using the 0.6m long ribbon cable supplied) to a separate Touch Keypad Board with 9 touch pads. If an incorrect digit is pressed the lock is automatically reset.
A PP3 battery clip is included for demonstration purposes. A mains adapter is recommended for long-term use.