A musical electronic lock
Beep, beep… Sesame
A motorised gate is jolly useful, just so long as you don’t forget the remote control or the key. Normally, the control system for this type of gate makes provision to connect a push-button for opening or closing it without needing a remote control or key. This button must not be accessible from outside, whence the need for a more complex system. The code lock suggested here lets you control up to three such gates using push-buttons after entering a valid secret code.
Materials
Gerber file
CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor GREEN and GOLD members can exclusively download these files for free as part of their membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service.
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Extra info / Update
* four codes with up to 15 digits
* three individually-driven floating contact outputs
* plays the March of the French Foreign Legion
* PIC16F84 microcontroller
* no critical components
Component list
R1 = 22kOhm
R2–R5 = 10kOhm
R6 = 56Ohm
R7 = 3.3kOhm
R8, R9 = 2.2kOhm
Capacitors
C1 = 470µF 25V, radial
C2 = 22µF 16V, radial
C3, C4 = 100nF
C5 = 100pF
C6 = 330µF 16 V, radial
Semiconductors
B1 = W06M bridge rectifier, 800mA
D1 = 1N4001
D2,D3,D4 = 1N4148
IC1 = 7805
IC2 = PIC16F84-4/P, programmed, Elektor # 081143-41
T1,T3 = BC337
T2 = BC547
Miscellaneous
P1 = 10kOhm horizontal multiturn trimpot
RE1,RE2 = 5V SPNO relay, 500Ohm coil, Meder type DIP05-1A72-12D
RE3 = 12V DPDT relay, Tyco type V23057-B002-A201
K1,K2,K3,K6 = 2-pin PCB screw terminal block, lead pitch 0.2 inch (5.08 mm)
K4 = 2-pin pinheader, lead pitch 0.1 inch (2.54 mm), with jumper
K5 = 10-pin pinheader, 10 contacts, lead pitch 0.1 inch (2.54 mm)
Loudspeaker, 50Ohm impedance
Numerical keypad, 4x3
PCB, order code 081143-1
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