Practical gated burglar alarm circuit diagram
Posted on Mar 28, 2007 11855
Under: Alarm Circuits
Circuit as shown by the triggering device, monostable delay circuit, the alarm sound generator, audio amplifier circuit, light control circuit, partially blocking the preset ci
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rcuit and power circuit. When the door locked and a permanent magnet ZT normally closed reed AG in close proximity, ZT AG magnetic field lines resulting in two separate contacts, so IC1A of foot was high, IC1A in the reset state, which output terminal pin is low, no VS triac trigger current blocking, it lights H is off. At this time no bias transistor VT1 off, VT2 are conduction, so IC1B of 12, feet was high (greater than 2/3 of the supply voltage), it is also IC1B the a feet output low, audio IC IC2 does not work without power.Once the door is opened, resulting in ZT AG and separated the two contacts within the AG naturally turned on, the cause IC1A pin goes low (less than 1/3 of the supply voltage), then immediately set IC1A, IC1A of feet from the original low to high, it is divided into two branches: one triac trigger VS conduction, H lights immediately lit, which can be used for lighting by the door. If the door during the day, since the photoresistor RG resistance is very small, the partial pressure of R11 and RG VS is not sufficient to trigger conduction, so during the day the door, H may not light. Another way to make the current transistor VT1 conduction, VT2 end result, short condition C4 is released, power to the C4 charge through R6, at this time IC1B of 12, feet potential of getting low, when less than one-third of its potential power voltage, IC1B output terminal a pin goes high, then the IC2 power and get to work. There have been the end of IC2 T0 pulse currents, after amplifying transistor VT3, pushing J1 relay contact j1-1 move and opened, thus making the original lights become constant light flashing lights to enhance the tension when the alarm the atmosphere, the same O/P end to IC2 output audio alarm signal, the VT4, after VT5 zoom, push the speaker BL loud voice.The alarm device for some time, the thief away, its siren can be automatically stopped. This is because IC1A was monostable mode, be it O, feet charge voltage to 2/3 of the power supply voltage, IC1A automatically reset, IC1As feet will automatically revert to a low level.Preset locking circuit by the transistor VT6, VT7 composition, after turning the machine power switch S1, should press the switch near S2, so VT6, VT7 conduction, the relay J2 temporarily pull its contacts j2-1 off, cut off power alarm circuit, so the owner closed the set alarm time does not cause false alarms. When the door is good, C9 discharged, VT6, VT7 closing, J2 release, its contact j2-1 closed, the power supply of the oscillator circuit is automatically turned on, the machine is in the waiting state.Good quality as long as the entire circuit element, and the welding is correct, you can boot test, the first close ZT AG, close the power switch S1, H should not light goes out, then took ZT, H at this time should immediately lit (if in the daytime test application hooded black cylinder RG), and then press down S2, H at this time should be immediately extinguished, after waiting for some time, H lit again, after a period of time H is lit, the oscillator trigger job, issue loud siren sound, and by the constant light begins flashing H will come to create successful.Preset time determined by the blockade 0.7R10C8 value. IC1A monostable 1.1R2C1 working time is determined by the value, the delay time is determined by the flip IC1B 1.1R6C4 value, can be adjusted by experiment. IC2 operating voltage should not exceed 5V, plus R12 can be adjusted.Installation and UseAG should be installed on the door frame, ZT should be installed on the door leaf activity, the entire circuit can be loaded into a milky white plastic cover in the ceiling.When the owner went out pre-alarm, can be closed S1, then press down S2, so until then lock the door, the alarm will automatically enter the waiting state. When the home owner with a key to open the door, if it is at night, when the door H lights automatically light up, the owner found the indoor light switch, should immediately disconnect the hidden power switch S1, otherwise it will cause an alarm. And after the thief door, because it is not time to cut off the power switch on the alarm (do not know or could not get with a switch), it will be delayed several seconds after the siren rang out, attracting attention, to play a thief deterrent and to scare away.