Intruder detection & recording

[ss_rakesh]

Idea is to have transmitter and a reciever
Transmitter
Sits on door/wall.
Signal reciever when ever someone opens door or moves in that way
Problem is,
This must very compact.
Must take very less power.

Reciever
Drives an external device after some delay (which must be adjustible)
This also must take less power on standby mode.

Please sujjest how to begin?

 

[HiTech]

I'm getting the idea that Indian schools and those in it's surrounding neighbors must have the ElectroTech forum URL posted on every classroom blackboard, printed on the cover of every electronic textbook, applied as screensavers on student computers, and tattooed on student foreheads! Ok now on with the issue at hand:

How about this for $15 US currency:

https://www.harborfreight.com/cpi/ctaf/Category.taf?categoryid=770&pricetype=S&categoryname=HOME%20DETECTORS%20%26%20ALARMS

I have used this product with good results and you can't beat the price. The Chinese make this for pennies on the dollar and you couldn't obtain the parts alone for $15 at surplus prices!!

Completely wireless infrared alert system. Just place the sensor anywhere on your property and the receiver anywhere in your house up to 400 ft away.
The receiver makes a pleasant chiming sound when sensor is crossed. Weather resistant and requires one 9 volt and three C batteries **broken link removed**

 

[The Mad Professor]

Maplin.co.uk has something very similiar on special offer this month I believe.

 

[ss_rakesh]

I'm getting the idea that Indian schools and those in it's surrounding neighbors must have the ElectroTech forum URL posted on every classroom blackboard, printed on the cover of every electronic textbook, applied as screensavers on student computers, and tattooed on student foreheads! Ok now on with the issue at hand:
How about this for $15 US currency:

Reason for posting in this site is to do it on my own. not to by some readymade stuff .

 

[philba]

that's really great to hear. you'll have to forgive people here for assuming that you were looking for some one else to do it for you - there is a lot of cheating done via the internet. http://www.geocities.com/pcbs4less/schoolprojecthelp.htm

 

[Hero999]

Reason for posting in this site is to do it on my own. not to by some readymade stuff .

We are just recommending the best possible solution.

 

[The Mad Professor]

It's known as a "break beam sensor" and is well documented across the web