# 9 Burglar alarm circuits ideas

Here are 9 burglar alarm circuits you can look at as ideas. To protect your property from thieves or burglars. These circuits have a few components. So, it is not difficult to build or modify to fit your applications, from simple switching to touch-sensitive.

## Alarm circuit for forgetting to close the door

This is a door alarm circuit used to warn us when we forget to shut the door. By using a switch sticking to the door or door frame. When we do not shut the door properly. The circuit will emit a warning sound from a loudspeaker immediately.

How it works

When stick switches S1, at the door which in usual time switch still pressed. Then, the circuit will make the frequency upwards with Q1, Q2 C1. When the circuit will work to have current flow through R1 reach C1.

Which C1 do something charge enough. Then, there is current flow get along well with B of Q1.

It makes Q1 work cause Q2 lead current flow reaches a loudspeaker.

At the same time, C1 will discharge change R1, when a discharge is finished. It makes the voltage at a pin B of Q1 be valuable a little make Q1 and Q2 stop work.

And have current flow through R1 reach C1 again. The work in this character will cause the loud sound goes up.

But when shut the door make switch S1 pressed. The Q1 cannot work. Because the voltage at a pin B be 0V make the circuit doesn’t work. And, no sound comes out from a loudspeaker.

## Car Burglar system with start delay

This circuit can prevent car theft. By the delaying them, not to steal our cars easily. Which they can use in both cars and motorcycles, that uses a battery 12 volts and also cheaper, too.

The working principle

In Figure 1 is the Car burglar system with start delay. When we apply a voltage supply for the first time. The capacitor C2-22uF will delay time the circuit does not work immediately. Then C2 is discharged with a resistors R2-50K.

The complete circuit of Car Burglar system with start delay

Once through this period. The circuit will check an undulation of voltage. By having a potentiometer VR1-100K is adjusted a sensitivity. When the car starts to cause a ripple voltage. The undulate will be the C1 coupling a signal goes to pin 13 of IC1/1, by the passed way the VR1 and R4

IC1/1(LM324) is used to amplify the voltage out away pin 14 through R6 into pin 3 of IC1/2, so causes pin 1 of IC1/2 has high voltage. And is send trough R8, D2 (1N4148) into pin 3 so that pin 1 of IC1/2 has high voltage all time. The LED1 will glow to indicate to khow that the circuit ready.

The capacitor C4(47uF) will Be recharged through D3, R10.By takes about 10 seconds. So causes pin 8 has high volts send through R15 into pin B of Q1(C945) to drive relay works.

When the contacts of the relay tap for 10 second, LED will go out. Now if we connect it to the alarm circuit is noisy. The Q1 is pull the voltage at pin 9 through D5, R13, so cause pin 9 of IC1/3 has a lower voltage.

The C4 will be out of the R9 discharge for about 1 minute. The voltage at C4 is connected to pin 10 of IC 1/3 lower than pin 9, Makes pin 8 no voltage out. The Q1 stopped working at the same time. The relay contacts. They IC1 / 4, R16 and C5 to Stop detection. After the relay contacts. To prevent a repeat performance. The circuit will be checked again. The relay contacts are released, about 5 seconds.

## Car Burglar Alarm Timer Delay Using NE556

Car Burglar Alarm timer alarm system circuit , model to economize. This circuit convenients for to set up in an automobile. usually switch at set up keep with automobile door will the circuit closes. But in case of car owner opens in and out while note as a result have no result anything , because of the transistor model PNP to still don’t work. Because of 9 pin have high voltage.

But when switch the door any one open the circuit exceed time delay keep 5 pin of IC NE556 have low voltage to fully drive transistor circuit give relay work. The system will order to give the horn a car talks at one time to come to immediately. But if we shut the door a car or close S1 system stop work again.

## Alarm Sound With Control Switch

The heart of this circuit is IC No. 555. When the alert sound was working, even though the switch will continue to be the same, the sound still does not stop immediately.But it will stops automatically, when a set time period,Depending on the resistance of R3, the circuit so I set a time period equal to 1M for 1 minute 6 seconds.

The output of IC 555 is triggered by a positive voltage on pin 2,when all switches are connected together.When the something switch is cut off pin 2, it will be negative voltage and the trigger IC 555 will stop.

The C1, C4 to protects a noise signal from either switch, which may cause the alarm to be up. This circuit can be used with power supply from 5V to 15V depending on relay sure enough.

## Simple burglar alarm circuits

At this period the economy not good, Make have steal plentiful. We come to try build the circuit steal model to is simple better. The Alarm Sound (Super Bell) loud forever until will cut power supply to go out.

When the Switch of the magnet Senate was opened or strip metal torn. The R1 stand gives to get the maximum score. Discharge late beside one of the Switches of the Senate or zone metal goes out.

Devalue R1 until will begin to change the dot is born the sound, this circuit will use the electricity about 0.3mA that 6Volt use Relay 6V 500ohm.

When use voltage 6V – 9V use Relay 9Volt 1200ohm. When use voltage 12Volt, this not difficult circuit. Request a friend enjoys and safe from steal please sir.

If you want a basic than this circuit, here is basic it one transistor alike.

## Burglar Alarm model the circuit closes

This circuit works with battery 9V a piece is very small. For the work happens independently don’t be under house electricity. The circuit will make a noise to warn work as soon as , detect which be switch model usual close the circuit or aluminum, eliminated separate.

## Easy kick out steal

Although the prevent steal or Circuit this be model to be easy the system is simple. but I think it may help can protect your assets.

The principle is simple to be the system Close Wire Loop. It will make a noise to warn when the circuit torn, by this circuit , use the electric energy while standby very low 0.5uA only.

But when Relay work as a result use current about 70mA only. The usability can use in an automobile,house door, leak round a house or the other. When an electric line torn system , Relay command give beep danger circuit work immediately.

## Simple slant (tilt) alarm switch

This is a simple alarm circuit. This work, when the switch S1 (sensor) tilted away from vertical.The alarm stops when the sensor back to the old form.

S1 sensor is a mercury switch. The contact is normally closed. When the switch is placed in a vertical. Transistor Q1 acts as a switch off, buzzer immediately.

When the sensor back to the original vertical position. Completion of all the circuits can be packed into a small box. Which is used as a tilt meter.

## Protects steal touch model using IC741

Contain divide this friends many you may face a problem economical. A steal the very. Today I recommend the circuit that protects steal again model that interesting.

It is model to touch , the system will work when , steal touch at the metal detects in your car. When you see the circuit may like because use the equipment that seek easy be IC 741 very the circuit has tall many rapidity.

When human body which there is electronic signal flows through all the time , make that signal changes to come to at input change R4 to pin 3 of IC-LM741 make it works cause Q1 and oval RY1 work with.

The lead goes to are usable , friends fine VR1 for fix the rapidity has of the circuit. The detail is other see in the circuit.

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### 8 thoughts on “9 Burglar alarm circuits ideas”

1. hai we r in mini project @ nscet theni

2. tank yu vary mach this is very good circuit for my house thank nao my famiry is safe from burgahglly

3. Thanks for the free circuits m8. They are MLG and lit fam.

4. THANKS AM GRATEFUL .HELP ME SOME CIRCUITS