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Hi guys..!!
this is my 1st easy cheap n simple instructabel 
u need following components for laser burglar alarm-
1. LDR or photocell
2.printed circuit board
3.soldering equipment
4.2N3904 transistor
5.1000uF 35V capacitors
6.wires
7.laser diode
8. 9V battery and battery terminal
9. 9V buzzer
10. 5K( or more)  trim pot


n ur ready to go...........!!!!!!!!!!!! 
 

Step 1: placing components

Instructions

Things You'll Need:
1 650nm 5mw 12X30mm laser 1 3.2v AC adapter 1 1000uF 35v capacitor 1 5K variable resistor 1 2N3904 transistor 1 12v siren or buzzer - 102dB 2 small project boxes 1 black plastic tube 1 photocell 1 IC board 1 9v battery and clip Tape or adhesive velcro strips Hot glue
1
Connect a photocell to a 5K resistor. This will pick up the laser light and enable the alarm.
2

Use a 2N3904 transistor to link the resistor, a 1000uF 35v capacitor, a 12v siren and a 9v battery clip. The attached schematic should demonstrate how the parts come together. Use an IC board to hold them in place and make sure the board is small enough to fit into a project box. Do not connect the battery yet.
3
Cut a small hole into the side of the project box big enough to fit the photo cell. Glue a short (1-inch) length of black plastic tube on top of the hole. This will protect the photocell from any ambient light.
4
Mount the photo cell carefully in the length of tube, running the wires back in to the project box. Mount the IC board in the project box using hot glue, making sure there is enough room for all the components.
5
Cut 3 small holes in a second project box. The first should be large enough to hold a 5mw 12X30mm laser, the second should be large enough to hold a toggle switch, and the third should be just large enough to fit the wires from an AC adaptor.
6
Slide the positive wire from a 3.2v AC adaptor into the hole and connect it to the positive outlet from the laser. Positive wires are often marked by red insulation.
7
Connect the negative wires from the laser and the AC adaptor into a standard toggle switch. Secure them all inside the project box with glue.
8
Use tape, glue, or strips of velcro to mount the two project boxes on either side of the door you wish to protect.
9
Connect a 9v battery to the first project box and replace it in the exact position is was in.
10
Turn the laser on with the toggle switch and make sure it lines up perfectly with the photo cell. The alarm is now activated. If anything breaks the beam, the siren will go off.
http://www.ehow.com/how_4605253_laser-alarm.html#ixzz10QJog2zC
<p>Is this a continuous circuit(one u block the rays it doesn't stop beeping)</p><p>Our normal.</p>
<p>I want to buy the cuircuit can anybody help me to buy it from online sites plzz tell me now</p>
<p>what's the total cost of making this model. I want to make one for my science project.Can anybody suggest more projects for class seventh????</p>
<p>You can make a motion detector</p>
<p>i dont get how to connect the variable resistor to the photocell/LDR</p><p>can somebody please help</p>
<p>please give its working details</p>
<p>i have made the whole circuit, and there are no connection problems, but as soon as i plug in the battery the siren starts, even when the laser is pointed on the ldr.<br>can any1 please help?</p>
<p>your ldr might have been a damaged one</p>
<p>ebay have the 2n3094 or i can mail ya one.</p>
<p>i need help to complete this project</p>
<p>where can i get a 2N3904 transistor</p>
VERY NICE PROJECT...................<br>BUT PRANJAL R U FROM MAHARASHTRA?<br>
ya m frm maharashtra...( kolhapur)<br>frm where r u?
GOOD PRANJAL I M ALSO FROM KOLHAPUR..........WHERE DO U LIVE IN MH09 ?<br>WHERE AND WHAT R U STUDYING NOW ?<br><br>I HAVE DESIGNED THE PCB FOR THESE PROJECT.........IF U GIVE ME U R EMAIL ID THEN I WILL MAIL U THE PCB SCHEMATIC........DO KNOW HOW TO MAKE PCB'S ?<br><br>ALSO I HAVE UPLOADED MY FIRST INSTRUCTABLE - &quot;THE SIMPLE WATER DETECTOR EVER&quot; ON THIS SITE!!! U CAN SEE IT..............<br>
i live in mangalwar peth..<br>wer do u live?<br>m studin siploma in E&amp;TC 1st year in govt. polytechnic kolp.<br><br><br>i hv sm idea abt copper clad PCB's...<br>WHAT R U STUDYING NOW ?<br><br>i made solar power mobile charger, lie detector, audio amplifier....<br>( i nt yet gt solar panel for this........)<br><br>rply..
GOOD.........I LIVE IN DEVKAR PANAND AND I AM DOING B.E. IN INFORMATION TECHNOLOGY AT BHARATI VIDYAPEETH'S ENGINEERING COLLEGE (currently appearing T.E. ) AND ELECTRONICS IS JUST MY FAVOURATE HOBBY NOT A STDY PART..........<br><br>I HAVE ALSO MADE AUDIO AMPLIFIER USING TDA2822M.......<br><br>AND WHY R U NOT GOT THE SOLAR PANEL FOR U R PROJECT ?
k..<br>tel me hw to make pcb at home.. plz<br>n der is 1 problem also, wen i conect my cel to charger it shows bad charger contact aftr 1 minit.. wt can i do? n y dis is cause??? plz rply
i can tell u pcb making plz give me u r email id and cell phone no also if u have <br><br><br>actually the solar cells as charger for mobile phones never provides the constant / stable current and the problem that u r facing is may be either u r ckt problem or the type of solar panel used..............<br>
Mobiles need 0.7A to charge so a 9V battery or a solar panel is not a good option. I had tried it but my mobile charges and then stops, again it starts n this goes on. Btw I'm from Mumbai
see the same link here http://www.instructables.com/id/How-20-Make-a-Solar-Cell-Phone-Charger or also try efy.com<br>
also i am going to use stepper motors and first need is to build stepper motor controller ........if u know more about stepper motors and its controllers plz report me.........also i have made the small drill machine at home for pcb drilling.
this seems like a project kipkay did. itis the same picture too :/
yeah..!! i made few changes in this project....<br>i also watch ehow.com for info about that project
you didn't have to take kipkay's picture
I think all in all it is just a picture, things were different in this instructable than kipkays. I think we should just note that it is after all an instructable but I think all it is missing is credit to where credit is due. Beyond that there is nothing wrong with using a picture that's already been taken.
PLAGIARISM!!!!! don't steal other people's work and claim it as your own. <br>BTW, http://en.wikipedia.org/wiki/Plagiarism
plagiarism from kipkay not good for indian image. <br>sorry
MOLIM pomoc. ja ne znam sta znaci taj znak ground pored photocell. <br>Molim odgvor
Anyone Please reply
What if I want to put 24v DC input what will be the changes required please also illustrate with diagram for this input. needed exigently please
plagiarism from kipkay <br>
love see so many INDIANS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
If you want a reset switch, where do i plant it?:(
Why you want a rest?? The buzzer will stop automatically after few time &amp; it depends on capacitors u connected .. You can make a reset switch between ANODE of CAPACITOR AND GROUND TERMINAL to stop buzzer instantly. OK?? try it.. :-) <br>
wer these items can be purchased from dubai <br>
yes. off course u can.
can you give me the circuit daigram in bread board
u cn use givn diagram on breadboard as prototype...
I made one. And it Works!!??!! This is my first success for those what I made from internet. I'm Happy.Very happy.
i have much more successful n easy projects 4 u dude...!!!
nice na?
nice project :) - will a cheap laser pointer do ?<br><br>http://www.scitoyscatalog.com/Merchant2/graphics/00000001/small_5_head_laser_pointer.jpg
hey in which country u r??<br>n tell me ur age plz..!!<br>:)
yes<br>i also used cheap laser...<br>

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Bio: Electronics is my passion...!!!
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