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

 
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Step 1: What You Need

Picture of What You Need
IntruderAlert_003.bmp
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.
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austech1 year ago
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?
sunofgod2 years ago
"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"
Is it possible to hook this up to a phone? So it calls you about an intruder while you are away?
tomtortoise3 years ago
does anyone know of a substitute for the transistor i cant find them at radio shack or online?
In a circuit such as this the transistor is not super critical. Use a PN2222 or even a 2N2222 and it will be fine.
Amazing!!!!
Aron3133 years ago
Nice!!!!!! :O
gjscholtz3 years ago
INTERRESTING PROJECT YET
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
eneergcam6 years ago
now you know when the crazy man down the street has gone crazy and is planning to kill you with an axe!
what if he goes around it though?
you would have to know it's there. or you could just jump over it
Yeaaahhh, i didnt think about that....know i only have one arm :(
oh no! you better duct tape it back on! lol

maybe you could surround your house by building a few of these
I thought it is spelled ax not axe. Axe is a brand of hair products
isnt this a time consuming door chime, chimes already do that.....
pastaking3 years ago
Replace the chime with a relay detonating a firecracker. :D
edfel014 years ago
when the beam i crossed does the alarm continue to go off or just when the beam is crossed for that 1 sec.?
tomx63 edfel014 years ago
the chime sounds just once when activated.
why not just put a electric fence around your property.
not sure about leaving the extention cord & transformer outside .  ***electrocuted****
xproplayer5 years ago
arent those rather nice shoes for a murderer?
brand275 years ago
Can you use this to open something.. eg.. if the laser is broken it turns on a motor for a set period of time which opens the drawer? thanks
codz30 brand275 years ago
It should work with that setup, obviously changing the relay from turing on a switch to powering the motor/
For as long as the beam stays cut, the relay will be active.

(Please correct me if I am wrong)
is that you with the axe
I laughed my heart out when he said "alert you of people on your property" and some guy with an axe is walking toward his house. Classic
marc926 years ago
Neat idea, but couldn't this this be set off by a squirrel or some leaves breaking the beam?
Yes, but what's worse? Waking up in the middle of the night to find a squirrel on your driveway. Waking up in the morning to find $5,000 worth of tools missing from your garage. I think I'll take the first.
That's a valid point, but how often will a squirrel, or leaves or something else, set this off (and wake you up) at night. Compare that number to how often an intruder will wake you up, and this system could get annoying pretty fast.
you could just fix the problem and put it somwhere where the frickin squirrels wont go, and intruders will. there, satisfied?
I suppose... Where is such a place that you suggest?
Inside your house just outside any door would be a good area. squirrels dont usually commit B and E
wperry1 marc925 years ago
You could just set it up so that the tx/rx boxes are higher up. You may want to place them 3' up or so so that neighborhood cats can also walk under it.
hockeyman125 years ago
Can someone who built this make this more clear because I have no idea how to make it but I really want to make one.
Highjump445 years ago
can some one do a vid of them setting this up on a board and soldering it
craig35 years ago
I'm sorry to post irrelevant stuff but i noticed your zildjian shirt, do you play the drums? How about an instructable to set up a double kick? i was trying to set mine upp at school and its really hard to get it right with the snare legs in the way
zhgutas6 years ago
K, I've a question. so does the LED on a receiver is lit all the time, and dims when the beam is broken, thus, decreasing the resistor value and letting the current flow, or does the LED light up, when the beam is broken? I'm asking, 'cause I was thinking this receiver design could be used with the laser system, also posted by kipkay, and it looks much more simple as well.
revhead zhgutas6 years ago
you can make an LDR circuit to trigger in either way, when it is very bright or when it is very dim. its all about the placment of parts. you said you where intersted in making a laser alarm system, well you should check out my instrcutable. i made a more advanced version of kipkays laser sysem which works much better. tell me what you think.

http://www.instructables.com/id/Laser_Beam_Alarm_System_with_Rechargeable_Battery_/
DrHoppe6 years ago
Love the intruder with the ax... You never know when a violent ax murder is going to walk up your driveway! However, this instructible is very cool. I think I can modify this to use as a trainer to keep the cat off the area rug he likes to pooh on...
Mr. Squishy6 years ago
This project is good for house protection! Someone that was building a new house across the street has parked in our driveway without permission a few times. Once I saw 2 girls with their bikes riding on peoples driveways. They went on ours. And also, sometimes people drive on our druveway to turn around. This project is great so we always know when people are on our driveway. Only problem is that cats walk on our driveway and we would always know when cats are on our driveway which we dont care about.
raise the sensor up to above cat level
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