Laser Alarm Circuit Assistance

J

jeznut

New Member

• Jan 30, 2009

• #1

Hi,

I am making a school project in which I want to make a circuit where a laser can trigger off an alarm. That is, if i step through OR on this laser beam, a loud alarm will occur.

The problem is, i don't know how to read and decipher some circuit as well as the different components. I have to admit i have insufficient "knowledge".

Is it possible to get any assistance?

Thanks

 

duffy

Well-Known Member

• Jan 30, 2009

• #2

Sure! You want to aim the laser at a light sensitive device, like a phototransistor or a CDS cell. The laser turns the device on, then you invert the signal so it's off until someone breaks the beam. Post the circuit here, tell us what you want to know.

 

J

jeznut

New Member

• Jan 30, 2009

• #3

well that's the problem, i don't know how to make a proper circuit...

 

C

colin mac

New Member

• Jan 30, 2009

• #4

A more practical way would be to use a PIR module instead. Trying to line the laser and detector will be a nuisance. A PIR module has a wide viewing angle and is self contained.
Mine can be powered off 4 to 12V and gives a high and low output.

 

J

jeznut

New Member

• Jan 30, 2009

• #5

Colin mac, how would i construct a proper circuit for this with the inclusion of the PIR module?

What module is good for this?

Also, was laser source should be used?

 

duffy

Well-Known Member

• Jan 30, 2009

• #6

That one doesn't use a laser. It's a body heat detector.

A more practical way would be to use a PIR module instead.

Click to expand...

Yeah, but loses points for style. He wants to goof with tripping laser beams, which is totally badass.

Here's a laser detector project with pictures, schematics and even a video -
Robot Room: Laser Pointer Remote Control Circuit

 

Last edited: Jan 30, 2009

J

jeznut

New Member

• Jan 30, 2009

• #7

here, i made this circuit. i think the circuit was done incorrectly tho...

**broken link removed**

i was planning on using these items:

1000uF 35v Capacitor
1 5K Variable Resistor
Photocell
9v battery and clip
1 N3904 Transistor
Toggle switch
12v DC Piezo Siren - 102dB
650nm 5mw 12X30mm laser (any better types?)
3.2v AC Adapter