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Friday, January 01, 2010

Simple door Alarm circuit


This is simple door alarm circuit.You can attach this circuit for your for your main door If somebody opens it alarm will activate.Sw1 is a Read switch.Those switches are operated with magnets.







Parts:

Q1 = BC547
Q2 = BC327
B1 = 3V Battery
R1 = 330K
R2 = 100R
C1 = 10nF-63V
C2 = 100uF-25V
SW1 = Read Switch



Note

# Don't supply more than 4.5V for this circuit

#Attach a magnet for the door frame near by the read switch

23 comments:

Unknown said...

where can I place a rheostat in order to lengthen the noise emitted by the speaker? (by R1 or R2 or C1 or C2)

Zam said...

you can fix a rheostat between C1 and the speaker.

Unknown said...

Hi, I would like to know the specific functions of each component in this circuit(R1,R2,C1,C2) and why wouldn't a 3V battery source make the speaker sound but a 1.5V Battery source would.
Thanks a million!

Unknown said...

Hi, I would like to know the specific functions of each component in this circuit(R1,R2,C1,C2) and why wouldn't a 3V battery source make the speaker sound but a 1.5V Battery source would.
Thanks a million!

Zam said...

yes you are correct.We can use 1.5V to make a sound.Here I have used Q1 and Q2 to amplify the signal which comes from read switch.

Unknown said...

can i replace the bc327 with a bc558? please reply soon.

Zam said...

No you cant use that

diana03 said...

where can i get a PCB layout for this circuit diagram???

sreenath said...

please explain me the working of the entire circuit.......

Zam said...

Read switches are some switches which can activate(on/off)by using magnetic power.Here firstly we give the signal to Q1 But out put power is not enough so we have used the second Q2 to generate the power.then it gives enough power to the speaker.If you have more questions don't hesitate to contact me

sreenath said...
This comment has been removed by the author.
sreenath said...

in R1=330K & R2=100R what K & R refers to.... and c1 =10nF-63V,isn't it 10micro farad and not nano.. and how the capacitors are useful here... please explain.....thank u...

lovethief.143 said...

how can i increase the volume

Zam said...

Hi,

You can use the similar transistor for Q2 which has high out put( high W ).Right now I can remember a number for that but by using transistor data book you can do it easily

amalpj said...

can i know the specification of speaker used ?

John b said...

Hi i was just wondering if you could put a timer in this circuit so that the alarm would not go of straight away but instead after say 5 mins? if so where would you put the timer?

Zam said...

simply I'll give you a method.But this is not a long timer this will work for one or two min.use a capacitor(250uf) to the speaker.

Anonymous said...

Nice Circuit.......

Raazi said...

From we get the read switch and what is the specification of it.?

Raazi said...

Srry not from we its from where we get the read switch..ok..

Unknown said...

can anyone explain how the circuit work
i m a beginer
thx

Unknown said...

Hi, Can anyone say me, why the circuit includes a resistor R2 and capacitor C2? What do they make, please?

Unknown said...

can we replace reed switch with limit switch?

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