This circuit is a circuit diagram of an alarm system which has 6 independent zones, timed 1 entry / exit zone, a 7-segment LED display. Suitable for small office or home environment, can also be adapted to use a combination lock or keypad to set and reset the alarm. Each zone Z1 to 6 have their own indicators. Switch S1 is a single pole, double throw switch. One position is set, the other is reset / unset. This is the figure of the circuit;
Switch S2 allows a “manual” test to test all zones and screens. Zone 1 has been independent and out of time. Zone 1 is a timed zone which must be used as a point of entry and exit from the building. Straight 2-6 zone is the zone, which will trigger the alarm without delay. Some RF immunity provided for long wiring run by the input capacitors, C1 – C6. Key switches, S1 acts as the Set and Reset / unset switches. For the best security to this type of metal with a key switch. All IC’s except IC6 is a type of CMOS buffered output, is denoted by the suffix “B”. Unbuffered CMOS IC that has a suffix beginning “U” and will not work in this series. IC6 is a 5 volt regulator provides power to the main CMOS IC’s.
In operation S2 is the switch can be set to “run” position. When keyswitch S1 is restarted, this is unset (off) state of alarm. In this condition the capacitor C8 will discharge through D9, R1 aand Z1 and capacitor C7 will be discharged through D8, R17 and S1. Would not relay RLY1 energy and all the CMOS IC and the display will not have power. When S1 is activated to regulate all CMOS IC’s receive a 5 Volt power. C11 will be a while charging and a low input signal applied to one half of U7A a CMOS4001B, dual input OR gate. U5A output would also lower (make sure all windows and doors closed zones 2-5) and the output of high U7A. U7A output is then inverted by U7B and again in February through R18 to the input latch circuit U7A maintain. U7B low output and so Q1 and relay RLY1 inactive and no alarm will sound.
Also, when S1 is set, slowly C8 charges through R13. C8 and R13 form out timer and allow time to clear the building. The delay is approximately 1.1 x the value of C8 (at UF), or about 52 seconds with the values shown. During the delay out of the zone Z1 can switch opened and closed without triggering an alarm. After the exit time expires, the C8 will be filled and one half of the 2 input AND gate, U5A will be high. Each opening of zone 2 to 6 will cause the alarm to trigger and relay will RLY1 energy. If an intruder tried to break-ins through zone 4 for example, the output of U1D countries will change from low to high. When this happens, the signal transmitted by the high U2C triple input OR gate CMOS4075 and sent to the input D2 in the BCD to Decimal CMOS4511 display drivers. D2 is a binary code for the four and the LED display will illuminate the figure 4. High output from U2C also forwarded to U5A, another triple input OR gate. Output of U5A is now sent through S2 to input from U7A. U7A and bistable latch formed U7B, changes in circumstances that cause the output to change U7A low, the output from U7B to be high and feedback through R18 to the input of U7A again. The circuit is now locked in a high state. High output U7B do two things. First, in Q1 switches and alarm relays RLY1. Both high output applied to the blanking U7B input from CMOS4511B through S2 and also to enable the pins attached. View now will continue to show triggered zone numbers, even if the zone is opened or closed switch again. This is a similar process for all other zones immediately.
Part:
R1, R4, R6, R7, R10, R11 = 100k
R2, R3, R5, R8, R9, R12 = 270R
R13 = 1M
R14 = 4k7
R15, R18 = 470k
R16 = 100R
R17 = 1K
R19 = 10K
C1, C2, C3, C4, C5, C6, C9, C11 = 100nF
C7, C8 = 47u
C10 = 100u
D7, D8, D9 = 1N4148
Q1 = 2N3904
RLY1 = Relay 12V Coil 500R
Z1, Z2, Z3, Z4, Z5, Z6 = Contact NC
S1 = SPDT
S2 = Degree DPDT
U1 = 4050B
U2, U5 = 4075B
U3 = 4511B
U4 = 4081B
U6 = 7805
U7 = 4001B
BZ1 = Buzzer
