Psychological Car Lock

Common 789 456 123 N1...N4=IC1 = 4070 N5...N8 = IC2 = 4070 KO 9 K8 8 :75 21 D 44 1C2 0 0 r m02 D3 D4 .114 "14 Rs111 R70 98 ei R9 12V BC557 BC547 K1 K4 K7 IKO K2 K5 K8 K3 K6 K9 C547 • R14 1:(0 K1 K2 K3 K4 K5 K6 R10 R13 915 R12 R16 911 C5 C1 C4 C6 C3 C7 C2 R17 K7 K8 K9 R18 R19 C10 PSYCHOLOGICAL CAR LOCK The lock circuit is based on elementary psychology rather than on any recent development in electronics. The lock consists of a 12-key membrane keypad and an associ- ated visual indication circuit. The complete unit is installed in an out-of-the-way position below the dashboard in a car, where it is not too difficult for a potential car thief to spot. When the keys on the keypad are pressed, the impression is given that the lock will enable the car ignition when all four LEDS light. Because of the special configuration of the lock circuit, this will "never happen. Eventually, the would-be thief gets frustrated (we hope) and tries another car, not realizing that the lock circuit is ...