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Advice on building an autonomous sentry camera w/ laser Answered

I'm looking for some help/ advice on building an autonomous security camera that tracks moving object with a laser. much like this instructable, but with a laser instead of a gun: https://www.instructables.com/id/Autonomous-Paintball-Sentry-Gun/


as a bit of background, my house was recently burgled. ive now had a normal security camera installed on my house because of it, but would like something a bit better. i dont have that much knowledge on building electronic things (as i dont know where to start), so i am also looking to learn some things while i build this, instead of just following instructions and not knowing why im doing something. so first question is where can i learn about the basics? or would it just be a learn as im doing kinda thing. 

as for the actual sentry, i was looking for a little advice on how to build it as it wont be exactly the same as the link above. for starters i would like to use a laser instead of the paintball gun. this is mainly as a deterrent as i would assume someone is less likely to try and burgle their house if they know they're being watched/ tracked. 

the camera would also need to be a better quality one than a webcam, and would also need night vision. i dont really know how a different camera (not webcam) could be set up. building on this, could there potentially be issues with tracking at night?

when its built it will also be on all night every night, and mounted to the wall. what would be the best way of having it all mains wired as having to replace the servo batteries will be a massive pain in the ass.


i understand as i dont have that much knowledge atm that this will probably take me a while to build and perfect, but any help with the above points would be greatly appreciated! 

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caitlinsdad

4 years ago

From a security standpoint, you are better off investing in a better security camera, higher resolution or a wider field of view. Good systems have motion detection based on the image. I'm all for building a PTZ camera tracker but if a criminal knows the camera moves, he will get around it.

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scott08caitlinsdad

Reply 4 years ago

i have a camera on the back of my house which covers my whole garden, a camera on the side which covers the alley way and there is street cctv on the street that covers the front.

im just assuming that a camera with a tracker would be a step up from a normal camera, as the person knows the camera is on and working (as opposed to a dummy) and that potentially someone is actually watching them (as they may not know its autonomous as it isnt common). tbh, even if its no more effective than a regular camera (which i have now installed) it should still be a cool project to do.

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caitlinsdadscott08

Reply 4 years ago

No doubt the project would be fun and even a challenge. The problem is the implementation and possibly the law being on the side of the criminal. You would be the one menancing with a laser -no matter how low power or if it is unintentionally aimed toward the skies with air traffic.

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scott08caitlinsdad

Reply 4 years ago

as for legality, it was my understanding that lasers in the uk below a certain power (which i will have to look up) are allowed to be used within reason in public, and more powerful lasers are allowed to be used at home. it will probably be a 1mw laser.

i personally cant see an legal issues with this - the field of view of the camera will dictate where the laser is pointed, which will only be my own property, and even if something fails with the software the servos will physically limit the lasers range of motion anyway. Also, as the laser is not programmed to shine in to eyes of people and just at moving objects in general, i think i would be covered as there is no intent. The laser i would be using would be below the power threshold for eye safety, and i could also put a sign on my house warning of the laser to cover all bases

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Kitemanscott08

Reply 4 years ago

Even without the intent, there is still the risk. This being the UK, you would likely find yourself on the receiving end of a claim for damages, even if all that happened was an intruder got dazzled and stubbed their toe - don't forget, this is the country where a teen sued a council for damages after he was injured falling through their roof (his argument was that the council did not make a great enough effort to dissuade him from climbing onto the roof!).

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scott08Kiteman

Reply 4 years ago

with a 1mw laser (deemed safe in the uk), the range limited only to my own property, adequate warning signs put up on my back fence (as it will be for my garden), and the laser aiming for the middle of a target, and the fact that i wouldnt technically be controlling it, would it still be an issue?

i can put a pin in using a laser, and if it seems like there will be a legal issue ill just use something like a mini spotlight. so besides this i think my biggest questions are how i would go about using a better quality camera (as the instructable i linked uses a bad quality webcam), and how i would go about having everything mains powered instead of battery?

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Kitemanscott08

Reply 4 years ago

Just looking on the pessimistic side - you know how weird our laws get sometimes.

I can't really help with the electronics, but a thought does occur to me; motion following cameras normally need decent illumination and visual contrast to work reliably. Why not stick with a commercial PIR based camera and floodlight system, but wire a relay in parallel to the light to trigger a recording, something like "Look up here... Thank you, your images have been recorded by CCTV, and are being forwarded to the local police station. You may now leave."

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scott08Kiteman

Reply 4 years ago

yeah i thought of that too, but since the cameras ive seen on sentry guns havent been used at night time ill only really find out by doing it. i could potentially use a hd IR camera, and then put in a couple of IR lamps at the back of my garden (its not that big) which hopefully should be enough.

if that doesnt work then your idea is a good one to fall back on and ill be able to just use the same parts