VCO for Digitizing Analog (Isolation?)

Discussion in 'General Electronics Chat' started by Management, Mar 12, 2014.

  1. Management

    Thread Starter Active Member

    Sep 18, 2007
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    I have read that VCOs can be a simple and cheap way to digitize sensor data and send them over relatively long distances. I like the concept but I haven't read anything on such a setup providing isolation.

    Any thoughts and ideas on this?
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    What is a VCO?
     
  3. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    VCO is normally used for voltage controlled oscillator. I would normally expect to see one in an ANALOG circuit.

    To digitize ANALOG sensor data you would use Analog to Digital Converter, commonly abbreviated ADC.
     
  4. alfacliff

    Well-Known Member

    Dec 13, 2013
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    actually what you are needing is a voltage to frequency converter.similar to a vco, but optomised for telemetry.
     
  5. crutschow

    Expert

    Mar 14, 2008
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    As regarding isolation, that may or may not be required, depending upon the application. Typically the signal is not isolated, but if required, you can use an isolator such as an opto coupler for the digital signal output from the sensor to the receiver.
     
  6. t06afre

    AAC Fanatic!

    May 11, 2009
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    Perhaps you mean voltage to frequency converter in one end and the reverse in the other end. A typical circuit for this was this one. http://www.ti.com/lit/ds/symlink/lm231.pdf They also make an IC to match the function in the other end (dont remember the name) The IC was popular before micocontrollers took over such functions
     
  7. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    It's commonly done in industry, as a frequency signal can be very reliable over long distances.

    It's also common in sensors. A lot of the light sensing and colour sensing ICs have frequency output.
     
  8. Management

    Thread Starter Active Member

    Sep 18, 2007
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    This exactly what I was looking for. Very much appreciated.
     
  9. Management

    Thread Starter Active Member

    Sep 18, 2007
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    Any recommendations on an octocoupler that would be able to work with the mentioned voltage to frequency LM231's operating temperature of -25C to 75C or 85C?
     
  10. Management

    Thread Starter Active Member

    Sep 18, 2007
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    Another question, I need to sense overcurrent and trigger a contractor to open. Normally the contractor is normally open for safety releasing but kept open via PWM control signal.

    Any ICs available that can do current detection via differential voltage across a shunt and trigger a control to a contractor? Assuming the current needed for the contractor comes from a separate source.
     
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