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Motion sensor question.

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New Member
Hello, I wanted to detect very small movements, primarily of roaches, which i have an intense fear of. I live in a downstairs apartment and i believe the big roaches come from outside from under the door. I wanted to create something simple that i could stick on the door which will be pointing downwards towards the bottom opening of the door.
I was wondering if there is any motion detectors out there that can pick up such small movements.
I have searched on the net and all i find is these big pre made sensors with the light fixture on it. I want a small IC type sensor that i can manipulate and connect to a PIC, then an alarm sounds or something, then i can wake up and spray the roach. Thanks again
They come in from my door at a rate of about 1 every 2 to 3 days which i think is very frequent. I hate this new apartment for that.


Active Member
Detecting them isnt going to stop them from coming. I'd talk to your land lord or whoever about installing a piece of weatherstripping on the bottom of your door to prevent them from coming in. Shouldnt be very hard to install, I dont even think you have to take the door off the hindges.

Maybe you can hack a light motion sensor and just set it to be very sensitive.

panic mode

Well-Known Member
eew... nasty :cry:

i hate bugs myself and i would definitelly move away instead of trying
to fight someone else's war. also i would't like to wake up every other
night turn, jump, search for light switch and spray can and run around
looking for bug running away from sound alarm.
that's how psychos are made :lol:

but if you want to try something i guess you could use simple beam
through sensor and buzzer.

once i heard guy claiming to have used it to trigger inverter with
high voltage to kill the pesky critters on spot. he said he had some
sort of brush that was actuated after every kill to remove dead bug
from sensing area.


Active Member
Look @ my little alarm project here. it will sense the bug and set off the buzzer for like 9 seconds. Just make sure you have a loud enuf buzzer to wake you up. No PICs or anything, just real simple.


If u haven't guessed already, just place the LDR on one side of the door and the IR LED on the other.

if i were u, i'd just install some weather stripping. I had the same problem. My family and I had to live @ my uncle's house once and one night I woke up to something moving around under the covers. When i jumped out of bed, I found a HUGE spider crawling around. To make things worse, in the morning, I woke up to a spider staring at me on my pillow. Weatherstripping was installed promptly :lol:


New Member
Zachtheterrible, your link does not work. Could you update it?
Thanks for the suggestions. I will put a weather strip but i would still like to make this thing. It would be something cool to have for the future. I have such an intense fear of roach its not even funny. Some of you probably have had similiar experiences but my fear is so great that i often dream about the roaches when they are around. Like last night i dreamt that a roach walked into my room ( this is my version of a nightmare) so i got up turned on the light and 5 secs later a thick juicy fat roach comes walking from under my room door into my room. I have had similar dreams in the past that predicted my encounter with roaches. I guess it is a defence mechanism lol.


New Member
Roaches are electro sensitive like most insects. If you think about it you can use electricity to your advantage here.


Active Member
works fine for me. if that doesn't work, just go to the projects section and look for the one that says "laser or IR beam alarm system"

i like the idea of electrostatic detection, u could put a piece of metal under the carpet and the roach would be sensed.
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