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...........!!!!!!!!!!!!
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Signing UpStep 1: Placing components
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





































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i also watch ehow.com for info about that project
BTW, http://en.wikipedia.org/wiki/Plagiarism
sorry
Molim odgvor
BUT PRANJAL R U FROM MAHARASHTRA?
frm where r u?
WHERE AND WHAT R U STUDYING NOW ?
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 ?
ALSO I HAVE UPLOADED MY FIRST INSTRUCTABLE - "THE SIMPLE WATER DETECTOR EVER" ON THIS SITE!!! U CAN SEE IT..............
wer do u live?
m studin siploma in E&TC 1st year in govt. polytechnic kolp.
i hv sm idea abt copper clad PCB's...
WHAT R U STUDYING NOW ?
i made solar power mobile charger, lie detector, audio amplifier....
( i nt yet gt solar panel for this........)
rply..
I HAVE ALSO MADE AUDIO AMPLIFIER USING TDA2822M.......
AND WHY R U NOT GOT THE SOLAR PANEL FOR U R PROJECT ?
tel me hw to make pcb at home.. plz
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
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..............
but still its showing bad contact...........
plz tel me solution as early as possible..
did u searchd for laser alarm or its randomly cm in project list??
audio amplifier..
aftr 26 dec......
http://www.scitoyscatalog.com/Merchant2/graphics/00000001/small_5_head_laser_pointer.jpg
n tell me ur age plz..!!
:)
i also used cheap laser...