Intruder alarm

[krys]

I found this schematic on the internet. I'm thinking about adding some features such as making it auto on during the day and off during at night. I understand that I have to use a counter. Can you please tell me what counter do I need to use and where do I connect them to the circuit. Thank you.

http://www.circuitstoday.com/super-sens ... uder-alarm

[Brian Griffin]

I found this schematic on the internet. I'm thinking about adding some features such as making it auto on during the day and off during at night. I understand that I have to use a counter. Can you please tell me what counter do I need to use and where do I connect them to the circuit. Thank you.

http://www.circuitstoday.com/super-sens ... uder-alarm

If you need to turn it on at day and turn it off at night, you may need to use an RTC (Real Time Clock) chip such as DS1307 or equivalent. It is much convenient than the counter itself.

Of course, use a microcontroller too. It'll be much easier that way.

[ABSF]

How are you going to power your circuit? If you are powering your circuit using an AC adaptor, there is a power socket with timer That you can buy. The timer can be digital with a small keypad and LCD. The analog one comes with a wheel with teeth where you can push or pull them in or out to ON or OFF the timer. Each tooth represents 15 minutes. Just plug your adaptor on top of the timer and set the ON and OFF time.

If you want the whole thing Battery operated. Do it as suggested by Brian using a clock and a PIC. Since the job is very simple a 16F628a and DS1307 should do. you'll need a few switches to set the present time as well as the ON and OFF time. Not sure whether you need a LCD display to see the time or some LED to indicate that the clock is running.

Allen

[Brian Griffin]

How are you going to power your circuit? If you are powering your circuit using an AC adaptor, there is a power socket with timer That you can buy. The timer can be digital with a small keypad and LCD. The analog one comes with a wheel with teeth where you can push or pull them in or out to ON or OFF the timer. Each tooth represents 15 minutes. Just plug your adaptor on top of the timer and set the ON and OFF time.

If you want the whole thing Battery operated. Do it as suggested by Brian using a clock and a PIC. Since the job is very simple a 16F628a and DS1307 should do. you'll need a few switches to set the present time as well as the ON and OFF time. Not sure whether you need a LCD display to see the time or some LED to indicate that the clock is running.

Allen

And, if to interface the whole circuit with other high-voltage elements, use a relay too.

[krys]

How are you going to power your circuit? If you are powering your circuit using an AC adaptor, there is a power socket with timer That you can buy. The timer can be digital with a small keypad and LCD. The analog one comes with a wheel with teeth where you can push or pull them in or out to ON or OFF the timer. Each tooth represents 15 minutes. Just plug your adaptor on top of the timer and set the ON and OFF time.

If you want the whole thing Battery operated. Do it as suggested by Brian using a clock and a PIC. Since the job is very simple a 16F628a and DS1307 should do. you'll need a few switches to set the present time as well as the ON and OFF time. Not sure whether you need a LCD display to see the time or some LED to indicate that the clock is running.

Allen

I did plan to just connect it to adapter - which is stick to the old circuit and make it manually on and off. But I think it's not really that practical. Could you explain more about the teeth-adaptor thing?

[ABSF]

This is how it looks like

timer.jpg (25.98 KiB) Viewed 5593 times

This is the digital version

418U4DgLdvL._SL500_AA300_.jpg (8.24 KiB) Viewed 5590 times

Allen

[krys]

Thanks.

[krys]

I already constructed the circuit. My problem is that when I connect the circuit to a 9V dc source, the buzzer buzz non-stop. I think it's because of the surrounding light. How should I resolve this problem? I mean...how should I make the circuit only trigger by abnormal light instead of surrounding light such as the sun or the moon?

[ABSF]

I already constructed the circuit. My problem is that when I connect the circuit to a 9V dc source, the buzzer buzz non-stop. I think it's because of the surrounding light. How should I resolve this problem? I mean...how should I make the circuit only trigger by abnormal light instead of surrounding light such as the sun or the moon?

Ok I'll tell you how to trouble shoot the circuit.

First remove the buzzer if it is making too much noise. Connect in the power supply say 9V. Get a digital meter ready. Pin 2 of the op-amp 741 should be half of the supply voltage ie 9/2=4.5V . Then measure pin 3 of the op-amp. On normal ambient light, the LDR should be below 1000 ohms. So adjust R9 until the voltage on pin 3 falls just below 4.5V. If you are not able to get it below 4.5, get another pot of 1K and connect it in series with R9. temporarily short R9 with a wire soldered with 2 crocodile clips. Adjust the 1K pot until the LED goes off. Then cover the LDR with your hand and the LED will be lighted again.

The reason you have to keep R9 because if the alarm is to be used at night, you might need it as the ambient light is lower. So I guess you didn't read the web-site carefully as it was all mentioned in your web site.

Notes
To setup the alarm ,power up the circuit and adjust R9 so that LED  D1 goes off.
The LDR can be housed in a dark tube to increase sensitivity.
The sensitivity is very important here. If you cannot adjust the required sensitivity properly, use one LOW resistance (~1K ) POT in series with  R9 for fine adjustment.

Allen

[royalstorm7]

krys
if want to ignore all the lite stuff, u should turn to PIR sensor....and using timer to register the nite and day...or as alternative u can use photo sensor from electrical shop (normally for street lighting) to detect the day and nite.....ez bro

tq
roslan
royalstorm7@yahoo.com
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