Electronic Simple Code Lock

Wednesday, February 7th, 2018 - Protection Circuit

The electronic simple code lock circuit described here is of an electronic combination lock for daily use. It responds only to the right sequence of four digits that are keyed in remotely. If a wrong key is touched, it resets the lock.

Electronic Simple Code Lock Aplication

  • Key to the house
  • Locks on cabinets
  • Combination lock for motorcycle
  • Combination lock for safetybox
  • Combination locks on drawers

The lock code can be set by connecting the line wires to the pads A, B, C, and D in the folowing picture. For example, if the code is 1756, connect line 1 to A, line 7 to B, line 5 to C, line 6 to D and rest of the lines—2, 3, 4, 8, and 9—to the reset pad as shown by dotted lines in the folowing picture.

Electronic Simple Code Lock Circuit

Electronic Simple Code Lock Circuit

The electronic simple code lock circuit circuit is built around two CD4013 dual-D flip-flop ICs. The clock pins of the four flip-flops are connected to A, B, C, and D pads. The correct code sequence for energisation of relay RL1 is realised by clocking points A, B, C, and D in that order. The five remaining switches are connected to reset pad which resets all the flip-flops. Touching the key pad switch A/B/C/D briefly pulls the clock input pin high and the state of flip-flop is altered. The Q output pin of each flip-flop is wired to D input pin of the next flip-flop while D pin of the first flip-flop is grounded. Thus, if correct clocking sequence is followed then low level appears at Q2 output of IC2 which energises the relay through relay driver on electronic simple code lock circuit.

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