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Code Lock

Using a rotary encoder

Most code locks or electronic entry systems need a 10-way keypad to enter a code number sequence. This design performs the same function but takes a more circular route…Electronic lock or door entry mechanisms normally use a 10-way numeric keypad to enter the code sequence. Once the correct four-digit sequence is entered a relay is activated and this switches a door-opening device. A novel alternative to the keypad is a rotary encoder coupled with a left/right scrolling single character dot-matrix display to indicate direction of rotation and value of the encoder.
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Materials

Component list

Resistors:
R1-R7 = 47kOhm
R8-R14,R20,R21 = 4kOhm 7
R15-R19 = 150Ohm
Capacitors:
C1,C2 = 33pF
C3 = 1µ F 16V
C4,C5 = 100nF
C6,C7 = 10µ F 16V radial
Semiconductors:
IC1 = 74LS156 or 74HC(T)156
IC2 = PIC16F84 or PIC16C84A-4/P, programmed, order code 020434-41
IC3 = 78L05
D1 = 1N4148
T1-T7 = BC557B
T8 = BC547B
Miscellaneous:
X1 = 4MHz quartz crystal
LD1 = 5x7 matrix display (Conrad Electronics # 160490)
S1 = Rotary encoder type 427 (small model) (Conrad Electronics # 705594)
RE1 = FRS1B-S, 12V, 1 x changeover (Conrad Electronics # 505196)
JP1 = 2-way PCB terminal block with jumper
K1 = 3-way PCB terminal block, lead pitch 5mm
2 solder pins
PCB, order code 020434-1
Disk, source and hex code, order code 020434-11 or Free Download

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