DC to Pulsating DC Generator

Discussion in 'The Projects Forum' started by marvinsmith, May 8, 2016.

  1. marvinsmith

    Thread Starter New Member

    May 8, 2016
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    Hello,

    I'm trying to take a DC signal from a battery and convert to a pulse signal, essentially identical to a fully rectified A/C Signal. Any comments on how to do this would be appreciated.
     
  2. ronv

    AAC Fanatic!

    Nov 12, 2008
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    How about a picture of the output?
     
  3. marvinsmith

    Thread Starter New Member

    May 8, 2016
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    Hello,

    I want to make the following signal from a battery;

    2_16_0_11.png
     
  4. Sensacell

    Well-Known Member

    Jun 19, 2012
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    While you don't mention the desired voltage or frequency...

    The easiest way I can think of doing this is with a micro-controller.
    Connect a DAC, drive it from a SINE table stored in memory.
    If the desired frequency is low enough, you could use a PWM output instead of a DAC.

    Alternatively, (with more difficulty) you could use a sine wave oscillator and a precision rectifier circuit.

    What's this thing for?
     
  5. marvinsmith

    Thread Starter New Member

    May 8, 2016
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    I would like to power an electromagnet while also transferring energy through a set of coils, thus needing pulsating but also DC power.
     
  6. Sensacell

    Well-Known Member

    Jun 19, 2012
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    Then the output wave shape is of relatively little importance.

    If I understand your concept: you want an AC signal with a DC component to create a DC magnetic field, while also transferring some power through induction?

    Your biggest problem will be avoiding saturation in the magnetics.

    Cant help much more until you fully explain what you are trying to accomplish.
     
  7. marvinsmith

    Thread Starter New Member

    May 8, 2016
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    What I want to make is a solenoid in an electrically operated hydraulic valve that will also power an agitator feature when engaged.

    The system runs on 24 Volts (two 12 V batteries). When engaged, the electromagnet (primary coil) will switch the position of the valve by pushing a spool. At the same time i need to transfer power from the primary coil to a secondary coil installed on the spoil via induction, which in turn will power the agitator (simply mechanical turbine system powered by small dc motor but sealed).

    I'm not sure if this is possible to do the way I'm describing?
     
  8. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Interesting project. Apart from the difficulty of getting current to change in an inductor I think the inductive coupling of sufficient power will be a major challenge if the primary coil is moving relative to the secondary. Can you post a sketch of the spool/coils arrangement?
     
  9. DickCappels

    Moderator

    Aug 21, 2008
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    Some questions to help us out:

    What is the peak output voltage?

    What do you expect the peak current to be?
     
  10. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    The pattern you show can be created using software PWM in which the MCU produces small slices of that half-sine wave. You will see a similar approach for micro-stepping stepper motors.

    As to your more general application, are you trying to create dither to overcome the stick and release ("stiction") in your valve? Here is a high-level overview of that process: http://www.qualityhydraulics.com/blog/what-dither-versus-pwm/

    There are many links on the web that address its design.

    John
     
  11. marvinsmith

    Thread Starter New Member

    May 8, 2016
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    The peak output voltage should be 12 volt and peak current 2 amps.
     
  12. DickCappels

    Moderator

    Aug 21, 2008
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    Quick note: One problem with 6 kHz is that it is the range of most people's hearing.
     
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