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Air actuated switches

Discussion in 'General Electronics Discussion' started by Barry_L, Dec 13, 2016.

  1. Barry_L

    Barry_L

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    Dec 13, 2016
    I am working on a project that involves vaping I am looking to build something that will require the use a small air actuated switch so something that will turn something on a soon as air passes through it. Any ideas?
     
  2. KMoffett

    KMoffett

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    Jan 21, 2009
    "small air actuated switch"
    How small?
    What voltage and current switch?
    Maximum price?

    Ken
     
  3. Barry_L

    Barry_L

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    Dec 13, 2016
    Small enough to fit in small tube about twice the size of a straw. The switch just needs to turn on a chip that controls the Vape mod its self. Price.... For prototype 10 bucks. At bulk $1
     
  4. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    For one you can use a barometric pressure sensor. It will not detect the flow of air but the change in air pressure which is imho suitable for your application.

    Or use a fork sensor (like e.g. this one) and add a small flap that is outside the sensor's light path when no air flows, buit is drawn into the sensor's light path by the flow of air, thus interrupting the ligt path and giving a sensor signal.
     
    bushtech likes this.
  5. KMoffett

    KMoffett

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    Jan 21, 2009
    Berry,

    Must the switch maintain a closed contact while there is an increased negative pressure/flow or can it be a momentary pulse closure?

    Ken
     
  6. duke37

    duke37

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    Jan 9, 2011
    Consider a thermistor with a suitable circuit.
     
  7. Bluejets

    Bluejets

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    Oct 5, 2014
    Op is looking at changes in air flow
     
  8. duke37

    duke37

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    Jan 9, 2011
    Yes, he is wanting to detect flow. Heated thermistors will change temperature and therefore resistance with flow. I used such a device to measure wind speeds on a vehicle close to the brakes. It became known as the bee catcher.:)

    Variation in ambient temperature may cause problems.
     
  9. KMoffett

    KMoffett

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    Jan 21, 2009
    A thermistor Wheatstone bridge with two in the flow and two isolated works, and deals well with ambient. But needs to be powered and amplified.

    Ken
     
  10. BobK

    BobK

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    Jan 5, 2010
    How fast a response would a thermistor give? If he want to turn on the heater only when you inhale, the response has to be pretty quick, not seconds.

    Bob
     
  11. KMoffett

    KMoffett

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    Jan 21, 2009
    Bob,

    Tiny thermistors can respond in fractions of a second. That said. since the Wheatstone bridge would be quiescent at ambient, sucking in ambient air would do nothing. The bridge would have to be powered to self-heat two of the thermistors, so ambient air would cool them and change the bridge output. But this seems to be getting too complex and require more power that some type of mechanical on/off device.

    Ken
     
  12. Barry_L

    Barry_L

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    Dec 13, 2016
    Needs to supply continuos signal to the board
     
  13. Barry_L

    Barry_L

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    Dec 13, 2016
    These are amazing however very cost prohibited. The type of switch I am thinking of is all ready in use for corner store ecigs I am just not sure what they use.
     
  14. Barry_L

    Barry_L

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    Dec 13, 2016

    https://goo.gl/images/Fsw7QP As shown here
     
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