Sensors for lights on off (timer)

Discussion in 'The Projects Forum' started by gfun, Nov 10, 2015.

  1. gfun

    Thread Starter New Member

    Nov 10, 2015
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    Hello
    I have an idea, and dont know for where to start.
    Plan maybe try to use Hall Magnetic Sensor. Press button red led on and start counting for 60s. in this time frame you can turn it off by touching sensor. If not after 60s red led off and yellow is on. then you touch sensor yellow led off, green on and start timer for 5min. After that everything resets. green led off.
    What kind of parts i need to use it for timer. The thing is that it should be small and easy put around your arm. Any ideas ?
    [​IMG]
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    745
    Easily done with a pic, or other microcontroller, can be done with cmos CD4093 chips. Are you using touch sensitive sensors or skin resistance terminals on vero board.
     
  3. gfun

    Thread Starter New Member

    Nov 10, 2015
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    thinking to use A1120 magnetic sensor. I think I need 2 A1120 one S polarity and N . For red and green led.I can program all on one CD4093 ? All is new to me so a lot need to learn and read.
    Sorry for English its not my native :)
     
  4. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    Cd4093 is not a microcontroller, its a cmos logic gate chip, do you prefer to use a microcontroller or logic gates and timer chips?
     
  5. gfun

    Thread Starter New Member

    Nov 10, 2015
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    I have no idea. whats the easiest way ?
     
  6. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    I would say the micro is easier, its the programme thats the part to solve, you have already started the logic steps, just need to make the delays, and input testing loops,which programming language do you know?
     
  7. gfun

    Thread Starter New Member

    Nov 10, 2015
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    C++. I was thinking to use Genuino MICRO but is a little bit big. So maybe will try PICAXE-08M2.
    What is better to use NFC chip or Hall magnetic sensors ?
     
  8. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    Need to look at the datasheet of both sensors, and see which is best for your project, like sense distance, voltage, current drain..
     
    Last edited: Nov 13, 2015
  9. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    The CD4521 is a 24-bit CMOS counter that will take a 32 kHz crystal and count all the way down to an 8 minute period. This should be enough to be the timebase for the state machine, with some decoding gates for the states.

    ak
     
  10. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    For us really old people, I would use 3- 555's & one OR, first as 60 s one shot, ( red), OS, second RS FF (yellow), & third 5 m OS, (green).
    Sensor #1 resets #1 OS & #2 FF via. OR; sensor # 2 resets #2 FF via. OR, & sets # 3 OS...
     
  11. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    I wouldn't use a 555 for a delay longer than a minute, better using a cd4060, or as said earlier a microcontroller.
     
  12. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Time tolerance not stated. 5 min for a 555 = no sweat, I run them up to 3 hours.
     
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