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Topic: best way to sense someone entering a room (Read 3 times) previous topic - next topic


hello basically my project consists of a servo arm applying a sandpaper pad to some film reel thats playing on a projector whenever someone enters a room.
what I was wondering was would be the best sensor to detect that persons presence?

originally I though pressure pads under a carpet but the rooms is quite large , well large in regards to being throughly sensitive about 3 square meters and it seems like it would be quite expensive.

my next thought was infrared beams but then I'd have a similar problem of having to angle quite a few to ensure the room is covered at every point.

recently I have been looking at the ultra sonic range sensors on spark fun and they seemed like they might be appropriate.

any thoughts?



Ultrasonic, PIR, or maybe even a pressure plate(s). When I was 7 yrs old, I made a pressure plate, with just some tin foil, card board, cotten balls, a battery and a buzzer, and that seemed to work pretty well. My first attempt was just a bell on my door knob.
Created Libraries:
TFT_Extension, OneWireKeypad, SerialServo, (UPD)WiiClassicController, VWID


ok cool , how did you do that? my issue was I thought I'd have to buy 9 or so pressure sensors for every pad , which would be quite expensive

sorry i'm so new to this and barely know anything about electronics , but eager to learn. making my own pressure pads would definitely be fun I think.


Feb 01, 2013, 04:37 pm Last Edit: Feb 01, 2013, 04:40 pm by HazardsMind Reason: 1
It was a simple yet crude design.

  • Cardboard as the bottom plate

  • A few tin foil strips glued to it, with about a inch of space between them.

  • cotten balls spaced between the strips

  • Top cardboard had large sheet of foil glued on

  • Attach wires to foil strips, battery and buzzer

Think of it as a very flat contact button.
However, WE HAVE TECHNOLOGY  :smiley-eek:
Created Libraries:
TFT_Extension, OneWireKeypad, SerialServo, (UPD)WiiClassicController, VWID


Just think about it this way.  You have a conductor(tin foil) on the top and bottom plates(cardboard) with something separating them(cotton balls).  When you complete the circuit(push the plates together) the buzzer goes off.

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