Anemometer Circuit

Discussion in 'General Electronics Chat' started by cessna7, Jun 23, 2011.

  1. cessna7

    Thread Starter New Member

    Jun 20, 2011
    2
    0
    I have designed an Anemometer circuit using a reed switch (pulsed DC) anemometer which will hopefully activate a relay linked to a LM2907.
    Could anyone give me any advice on how to fine tune this circuit?
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
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  3. pilko

    Active Member

    Dec 8, 2008
    213
    20
    I assume the reed switch is pulsed by a rotating vane and the relay operates based on frequency set-point.
    Your diagram indicates that frequency is inversely proportional to R and C, therefore adjust one or the other.

    pilko
     
  4. Jaguarjoe

    Active Member

    Apr 7, 2010
    770
    90
    The relay will never, ever energize.
    How much current is going to flow through the output transistor with a 10k resistor in the emitter leg?
    Assuming your relay draws less current than that transistor is rated for, just ground the emitter.
    You also need a commutating diode across the relay coil. Inadvertantly that 10k resistor Homered by protecting the 2907 from buying the farm because it wouldn't allow the relay to energize.
     
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