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DiscoverCircuits.com -- Hobby Corner
Last Updated on:
Monday, March 26, 2012 06:56 AM
Hobby Circuits'
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More
Alarm Circuits
Bistable Multivibrator or Flip/Flop Circuits
Light Detectors or Optical Sensors |
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It's Time to Dust Indicator |
I thought about this circuit when I heard that a lot cleaning personal in hotels
were either dusting rooms more often than necessary or not enough. I have not yet
built and tested this circuit completely but in concept it should work. The circuit
draws very low current from a +3v battery and could be housed in a package similar
to a small ashtray. The assembly might be placed in a suitable out of the way area
to collect dust. It would alert a maid when it was time to dust the room. The
circuit detects dust with an infrared LED that is pulsed so its light shines onto a
smooth flat plate. Any dust settling onto the surface is detected by a
phototransistor, mounted at a 90 degree angle from the LED. When the dust reaches a
particular level, sufficient light is reflected into the phototransistor to change
the logic state of the circuit to an alarm condition. The alarm output could be
connected to a beeper, a flashing LED or to one of the LED flashing circuits in this
hobby circuit section. |
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Click on Drawing Below to view PDF version of Schematic |
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