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Using Frequency to voltage converter. LM2907

Discussion in 'Electronic Basics' started by [email protected], Aug 22, 2007.

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  1. Guest

    I bought a LM2907 and im trying to build a tachometer for a RC car.
    I've looked at the schematics and I've tried to test the ic by
    inputing a pulse of 1Khz , 250mVPP waveform in the input but i am not
    getting anything in the output. Do you guys have any suggestions in
    what i can do to try to test this IC correctly.
     
  2. Don Bowey

    Don Bowey Guest

    Post the schematic so it can be reviewed.
     
  3. John Fields

    John Fields Guest

     
  4. vorange

    vorange Guest

    from what i can tell, you got one input to the opamp which is the
    reference speed you want to be at. you got another input to the opamp
    which is its present speed. And you got the opamp's output
    controlling the flow of a bigger current through a bipolar
    transistor.

    but since there is no negative feedback shown, the opamp will be
    driven to the rails and the transistor will only stop conducting when
    the reference speed has been equalled or slightly exceeded.

    am i right here folks?

    PS : I'm just a newbie so please note my ramblings with caution.
     
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