Intruder Alarm

[Karthick Pandy]

http://www.engineersgarage.com/electronic-circuits/intruderalarm

What is the voltage of the capacitor(100 uF) they have used here?

In the circuit diagram they have given capacitor(100 uF) goes with 3rd pin of 555timer. But in the video C-100uF is connected to 6th pin of 555timer. plz explain. .?

[Ashutosh Bhatt]

i think there is some mistake in the circuit diagram

the IC is configured in monostable mode. so at pin 6-7 there must be a capacitor connected

[Karthick Pandy]

I tried both the ways. But still it doesn’t work properly. Any suggestion on the changes in circuit configuration?

[AJISH ALFRED]

Remove the end of capacitor from pin3 and connected that end of capacitor to pin6, it should work. If you still have confusion please refer any monostable circuit based on 555.

[Karthick Pandy]

Buzzer just simply goes on without any intruder, when I use in monostable based model.

[Ashutosh Bhatt]

there may be some other problem. its very simple and streight forward circuit

check voltage at pin no 2 of IC. it will be always low

[AJISH ALFRED]

Hi Karthick,

Lets fix it !! There is a short circuit shown between the emitter or transistor and 5V. Replace that short circuit path with a resistor of 330ohms or 1Kohms. 

[Karthick Pandy]

I tried all possible methods you have suggested! It doesn’t work. I have attached a image, just check it and give your opinion. Thank u all in advance!

wysiwyg_imageupload:14228:

[AJISH ALFRED]

Hi,

In previous posts I mentioned to connect a resistor 1K from emitter of transistor to VCC, it is not connected in the image. The positive pin of the capacitor should be connected to pin6 of 555 and the negative pin should be connected to the ground.

[Ashutosh Bhatt]

this is very easy and streight forward circuit to build-run and test. this should not create such big problem. if you just go through basics of IC555 you can easily build your own circuit. 

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