How Can I Modify an IR Burglar Alarm to Trigger When Light is Blocked?

[Hoogaloo]

Hello everyone,

I have a project in science and I am puzzled with something. I want to have and IR emitter and an IR detector to act as a burglar alarm that will activate lights and a speaker-like thing. The only problem is that the IR set that I am using opens the circuit until it gets enough IR light then it will close the circuit and allow the charges to activate. However I want the system to activate when the flow of light is stopped. Is there any way to do this?

Thank you very much.

 

[Averagesupernova]

Lets find out a bit more about your project. What kind of alarm/buzzer/indicator/etc. do you plan to use? Are you familiar with relays? This can most certainly be done, just would like to know more about your project in order to determine the best way to go about it.

 

[Hoogaloo]

Lets find out a bit more about your project. What kind of alarm/buzzer/indicator/etc. do you plan to use? Are you familiar with relays? This can most certainly be done, just would like to know more about your project in order to determine the best way to go about it.

Thank you very much for replying.

To start off I will just say that I only know the very basics although I am very eager to learn.

For the sound I haven't decided on anything in particular I was just planning on using a simple noise maker. (I'm sorry I can't be more specific.)

The plan is to have the Ir emitter/detector pair sitting on either side of a door/opening and they would be connected to a battery and the rest of the circuit. The lights and sound maker don't have and restrictions although the maximum amount of voltage I can use is 9v and it has to come from one power source.

Thanks again for your reply.

 

[davenn]

hi Hoogaloo

show us the circuit you are currently using
modifications will probably be pretty straight forward.
I assume you want the indicator/alarm to activate when the IR beam is broken ?
thats the normal way

Dave

 

[Hoogaloo]

hi Hoogaloo

show us the circuit you are currently using
modifications will probably be pretty straight forward.
I assume you want the indicator/alarm to activate when the IR beam is broken ?
thats the normal way

Dave

How do I show you the circuit? I only have a pencil drawing for the plan.

And yeah I want the circuit to activate then the beam is broken.

Thanks.

 

[davenn]

How do I show you the circuit? I only have a pencil drawing for the plan.

And yeah I want the circuit to activate then the beam is broken.

Thanks.

I use paintbrush in windows to draw circuits save them as a GIF file then up load them to various forums etc

here's a drawing I did for another person within the last few weeks
it will give you the basics on where to start

the trimpot can be used to adj the sensitivity

Using the NC ( Normally Closed ) contacts of a relay means they will be open whilst the relay is energised as the circuit gets an IR beam into the sensor.
When the beam breaks the relay will de-energise and the contacts will close and whatever alarm / lights you have in the relay circuit will get voltage via the relay contacts and operate

cheers
Dave

 

[davenn]

Now if you wanted the alarm bells / buzzer / lights to run off higher voltage then a minor mod to the relay contacts wiring would cater for that :)

D

 

[DaveC426913]

I use paintbrush in windows to draw circuits save them as a GIF file then up load them to various forums etc

here's a drawing I did for another person within the last few weeks
it will give you the basics on where to start


the trimpot can be used to adj the sensitivity

I suspect that the OP does not have the level of detail of actual circuit diagrams. He is expressing his project on a much higher conceptual level.

 

[Hoogaloo]

I'm sorry, I'm kind of confused. I tried to find a way I could draw out the circuit but I couldn't find an easy way it always looked really weird. I'm sorry! Is there any other way I could help explain?

 

[davenn]

ok no probs :)

draw it out neatly on paper and take a sharp/clear photo of it with your phone camera etc :) let us know when you have done that and we can talk you through uploading the pic
do you know how to resize a pic on your pc ? off the phone it will be huge 1000 or so pixels x 1000 or so pixels you want to get that down to 640 x 480 or similar size

Dave

PS DaveC ... I am getting sooo peved off having to relog in every 5 minutes
I cleared all the cookies even restarted the puter and still its happening

 

[Hoogaloo]

ok no probs :)

draw it out neatly on paper and take a sharp/clear photo of it with your phone camera etc :) let us know when you have done that and we can talk you through uploading the pic
do you know how to resize a pic on your pc ? off the phone it will be huge 1000 or so pixels x 1000 or so pixels you want to get that down to 640 x 480 or similar size

Dave

PS DaveC ... I am getting sooo peved off having to relog in every 5 minutes
I cleared all the cookies even restarted the puter and still its happening

There is my drawing sorry if it is not very clear I can try to explain things there if you need.

 

[davenn]

thats a good clear drawing well done :)

unfortunately tho making a system work isn't quite as easy as that
it does need something along the lines of the circuit I showed you in my other post

Do you have the electronics background for building a circuit like I showed you ?
or...
Do you have an electronics mate that could build it for you and help you get it working ?

Dave

 

[Hoogaloo]

Unfortunately I do not have any connections to someone with any electronics skills. I am sorry for my lack of experience. Do you still think you could help?

Edit: Signing off for tonight Thank you for your interest guys!

 

[Hoogaloo]

Still need a way to make this circuit work could anyone point me to an easy solution?

Edit: What parts will I need?

 

[dlgoff]

Still need a way to make this circuit work could anyone point me to an easy solution?

Edit: What parts will I need?

I think a better approach would be to use a passive infrared sensor (PIR sensor).

Apparent motion is detected when an infrared source with one temperature, such as a human, passes in front of an infrared source with another temperature, such as a wall.

These are typical of intruder alarm systems:

Regards

 

[Hoogaloo]

I think a better approach would be to use a passive infrared sensor (PIR sensor).



These are typical of intruder alarm systems:

Regards

Where do you think I could find one of those to buy? How to those work? Do they complete the circuit when it senses something in front of it?

 

[dlgoff]

Where do you think I could find one of those to buy? How to those work? Do they complete the circuit when it senses something in front of it?

You can purchase a variety of types from http://www.homedepot.com/Electrical-Home-Automation-Security-Alarm-Systems/h_d1/N-bm86Z5yc1v/h_d2/Navigation?langId=-1&storeId=10051&catalogId=10053&searchNav=true&cm_mmc=SEM|THD|VF|D27E|GGL|SecuritySurveillance&skwcid=TC|13168|%2Bmotion%20%2Bsensor||S|b|8781861157. http://www.homedepot.com/Electrical-Home-Automation-Security-Alarm-Systems/h_d1/N-bm86Z5yc1v/R-100654986/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053 is for $39. Do a google search on "buying motion sensor" and you'll get lots of hits.

Motion detection is a process of confirming a change in position of an object relative to its surroundings or the change in the surroundings relative to an object. This detection can be achieved by both mechanical and electronic methods. In addition to discrete, on or off motion detection, it can also consist of magnitude detection that can measure and quantify the strength or speed of this motion or the object that created it.

http://en.wikipedia.org/wiki/Motion_sensors

 

[Hoogaloo]

I think that would be kind of cheating because those things are already their own circuit. For this I was going to use something like this:
http://www.radioshack.com/product/index.jsp?productId=2049723

http://rsk.imageg.net/graphics/product_images/pRS1C-2110714w345.jpg

 

[dlgoff]

I think that would be kind of cheating because those things are already their own circuit. For this I was going to use something like this:
http://www.radioshack.com/product/index.jsp?productId=2049723

http://rsk.imageg.net/graphics/product_images/pRS1C-2110714w345.jpg

Okay. Then:

...it does need something along the lines of the circuit I showed you in my other post...