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How to Build an Electronic Combination Lock

Many hobbyists enjoy experimenting with electronics, especially homemade printed circuit boards, or PCBs. These boards can be built with a variety of different electronic components, such as resistors and capacitors. The circuit pathway within the board, matched with specifically positioned components, creates a working electronic. An electronic combination lock is a PCB kit that hobbyists can build to form a security device; a user inputs a pass code into the PCB to allow power to flow to an attached item.

Things You'll Need

Electronic combination lock printed circuit board
Soldering iron
Solder
6 resistors
2 capacitors
Light emitting diode
2 flip flop integrated circuit chips
Relay
Battery snap
Diode
Transistor
10 pin socket component
Wire
External keypad printed circuit board
9 volt battery

Instructions

- 1
  Place the resistors' wire leads into the marked resistor areas on the PCB. The resistors can be oriented in any direction.
- 2
  Solder the resistors into the PCB with a soldering iron and solder. Visually inspect each attachment point; the solder should fill the entire lead hole for the best connection.
- 3
  Repeat steps 1 and 2 for the capacitors, light emitting diode and diode. However, these components must be positioned within the PCB in a particular orientation. Match the component's orientation with the board's surface marking. Incorrect positioning will cause the board to malfunction.
- 4
  Repeat steps 1 and 2 for the transistor, integrated circuit chips, relay and battery snap. Follow the orientation markings on the PCB's surface to ensure that the components are not attached incorrectly.
- 5
  Repeat steps 1 and 2 for the 10 pin socket component. Solder a wire from the socket's pin 1 to the external keypad's pin 1 with a soldering iron and solder.
- 6
  Attach a 9 volt battery to the battery snap. The keypad should light up, indicating that the circuit is working properly.

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