Introduction: Infrared Intruder Alert

Picture of Infrared Intruder Alert
Stop intruders from trespassing on your property with this infrared alarm system.

Step 1: What You Need

Picture of What You Need

1. Garage Door Sensors like these
2. Wireless Doorbell Chime for $6
3. Photocell
4. Various components as shown in the schematic.
5. 5 Volt AC Adapter. You need a regulated supply so the voltage does not 'float'. A 1.0 Amp supply will typically be regulated.

Step 2: Prepare the Receiving Sensor

Picture of Prepare the Receiving Sensor

I tried to get inside the garage door sensor to access the circuit but after a bit of prying decided that it would be better to leave it intact and keep the waterproof design as it was clear the case was glued together. So, using a photocell over the receiver LED was the best option.

1. Epoxy the photocell to the receiver to prevent any light from getting to the cell. I also added some coats of spray paint as these cells are extremely sensitive to light.

NOTE: To see which is the receiver, you can power up the sensors by using 3-4 "AA" batteries (4.5-6 volts). Connecting a 100ohm resistor connected to one of the sensor positive (+) lines will tell you which is the receiver when they both light up.

Step 3: Build the Circuit

Picture of Build the Circuit

The circuit is designed so the photocell triggers the 6 volt relay which in turn closes the switch on the transmitter, sending the signal to the receiver and ringing the chime. I built it as small as possible because I wanted everything to fit inside the smallest Radio Shack hobby box.

Step 4: Finish It

Picture of Finish It

Install the new circuit along with the transmitter circuit inside the hobby box. I drilled 3 small holes. Two on the side for the wiring that goes to the sensor transmitter/receiver and power and one more hole on the bottom that the leads for the photocell would fit inside. I also used rubber grommets and silicone to seal those holes. I used "5-Minute" epoxy to glue the box to the bracket that came with the garage door sensors.

Step 5: Use It

Picture of Use It

Install the sensor transmitter and the receiver wherever you want to use it. They come with around 30 feet of wire. Power it up and when the beam is crossed, the doorbell transmitter should signal the receiver and you will hear a chime whenever the beam is broken.

I hope you enjoyed this Instructable!


nanda krishnan (author)2015-07-10

Thank u........

austech (author)2013-06-24

Replace the chime with several Li- Po batteries with a timed switch and a capacitor, put it at the entrance to your house, and when they arrive... Flaming doorway, what burgalar wouldn't think twice?

sunofgod (author)2013-02-28

"Epoxy the photocell to the receiver to prevent any light from getting to the cell"
This statement is confusing to me and a few others, surely this will block the receiver?, but after reading the preceding sentence
"So, using a photocell over the receiver LED was the best option"
I am no longer confused, If I may make a suggestion you could reword the statement.

"Epoxy the photocell to the receiver LED, to detect the LED turning, on and prevent any light from getting to the photocell"

GrimRipper1080 (author)2013-01-28

Is it possible to hook this up to a phone? So it calls you about an intruder while you are away?

tomtortoise (author)2011-06-26

does anyone know of a substitute for the transistor i cant find them at radio shack or online?

Jollyrgr (author)tomtortoise2012-10-25

In a circuit such as this the transistor is not super critical. Use a PN2222 or even a 2N2222 and it will be fine.

Husham Samir (author)2012-06-23


Aron313 (author)2012-03-03

Nice!!!!!! :O

black hole (author)2012-01-06

It's spelled both ways.

gjscholtz (author)2011-12-15

I have several questions:
1 Is the 100ohm used as a limiting resitor for Receiver??
2 Why is it not used for the Transmitter?
- Is the Transmitter and Receiver part of the garage door system??
If it is then glueing the photocell over the Receiver will cause the garage door not able to work.
3 What energizes the photocel - How? What light source is used? since the photocel is glues over the Receivers 'light input' so not allowing to get any light from the Receiver!
I drew your diagram out on a schematic to be able to folow the circuit closely and as I can see it when the phtocell is energized [ I donot know how?] This will turn on the transister and in turn will turn on the relay!!!!!
I dont see the connection of the circuit in rlation to the Transmittter and Receiver!
I believe if you drew a schematic of the entire circuit I'm sure that your project would be much clearer to understand!
At lest for me - thanks

eneergcam (author)2009-04-29

now you know when the crazy man down the street has gone crazy and is planning to kill you with an axe!

musick_08 (author)eneergcam2010-01-26

what if he goes around it though?

mcaliber.50 (author)musick_082011-07-19

you would have to know it's there. or you could just jump over it

eneergcam (author)musick_082010-02-01

Yeaaahhh, i didnt think about that....know i only have one arm :(

musick_08 (author)eneergcam2010-02-01

oh no! you better duct tape it back on! lol

maybe you could surround your house by building a few of these

tech123456789 (author)eneergcam2010-05-03

I thought it is spelled ax not axe. Axe is a brand of hair products

XWXAXDXEX (author)eneergcam2010-02-01

isnt this a time consuming door chime, chimes already do that.....

pastaking (author)2011-06-04

Replace the chime with a relay detonating a firecracker. :D

edfel01 (author)2010-06-16

when the beam i crossed does the alarm continue to go off or just when the beam is crossed for that 1 sec.?

tomx63 (author)edfel012010-12-06

the chime sounds just once when activated.

bowmaster (author)2009-06-22

M-16 with armor piercing ammo.

Thundertydus (author)bowmaster2009-06-28

Why AP? And why an M-16? You just need a long shelled silenced .17, Leave the neighbours wondering

J Moneyman (author)Thundertydus2009-07-28


bowmaster (author)J Moneyman2009-07-28

Or 1 gross tonne of C-4.

Thundertydus (author)bowmaster2009-07-28

30 gigaton payloaded warheads

bowmaster (author)Thundertydus2009-07-28

Lolz, that's the same power I use to open cans.

Thundertydus (author)bowmaster2009-07-29

dont say lolz

bowmaster (author)Thundertydus2009-07-29


lolz hehe im board

Hire Chuck Norris to round house kick them.

grimgroper (author)bowmaster2009-11-02

 zero creativity here... you guys need to watch more SAW

tomtortoise (author)grimgroper2010-08-31

I suggest you have a pit in the ground filled with punji sticks and tigers

bowmaster (author)tomtortoise2010-08-31

And ninjas.

tomtortoise (author)bowmaster2010-09-01

but ninjas don't need a pit for people to fall into they. work alone

bowmaster (author)tomtortoise2010-09-02

True, but they'd want to keep the Tigers happy by petting their heads.

eneergcam (author)bowmaster2010-09-03

Now were thinking

XWXAXDXEX (author)bowmaster2010-02-01

This is in the suburbs, most likely not to do but while in the woods thats a different story >:()

bowmaster (author)Thundertydus2009-06-30

Vulcan minigun.

imkwl12345 (author)bowmaster2009-07-14

wtf you dont have to have a massive gun to kill someone... did it ever occur to you, you could just use a knife?

bowmaster (author)imkwl123452009-07-15

Exacto blade catapult.

imkwl12345 (author)bowmaster2009-07-16


nobelium106 (author)imkwl123452009-08-18

check out the Ghurka Khukri knife. One of those in a good size would make the holder feel pretty safe

bowmaster (author)nobelium1062009-08-18

I *love* those.

bowmaster (author)imkwl123452009-07-16

Exacto knife blade catapult.

Thundertydus (author)bowmaster2009-07-16

Rechambered Vulcan minigun firing exacto blades

And catapaults...

add a modified drill in the place of the door bell and use it to pull a string that pulls the trigger on a blanked off M-16.(detterant instead of excessive force security law suit

What about using a cannon

bowmaster (author)tech1234567892010-05-03

No, a nuke on a 10 second timer.

And then shoots a 10 round burst after 5 seconds.

About This Instructable




Bio: Tinkerer, hackster and prankster. Hit me up on Facebook: Thanks for checking out my Instructables!
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