varying 0-5v controlled duty cycle PWM of 12v relay to ground, help

Discussion in 'General Electronics Chat' started by elRey, Feb 23, 2009.

  1. elRey

    Thread Starter Active Member

    Feb 23, 2009
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    Hello,

    Would anyone suggest a circuit for a PWM around a 556 timer that:

    • near full range duty cycle (~0% - ~100%) can be controlled by a varying 0v-5v signal
    • a way to adjust/calibrate input voltage vs. duty cycle (i.e. 1v = 20% duty or adjust it to 1v = 35% duty)
    • ~20Hz
    • the output would be using the 'on/high' part of the wave to ground a 12v to actuate a solenoid (factory boost controller for car).
    The voltage supplied to the circuit would be regulated by the car's ECU at 5v.

    Thanks,
    Rey
     
    Last edited: Feb 23, 2009
  2. h.d

    Active Member

    Oct 22, 2007
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    the 12V solenid is not problem
    you can connect a FET or BJT with the digital controller output, and connect the solenoid with it on high or low side.
     
  3. gub2

    New Member

    Feb 28, 2009
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    Hi Rey,

    I am looking for a similar circuit to convert a 0V to 5V (Airflow sensor output) to Duty Cycle / PWM.

    Any suggestions or links?

    Paul.
     
  4. elRey

    Thread Starter Active Member

    Feb 23, 2009
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  5. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Voltage to PWM , just an outline, but it works fine on my electric tractor. Best if 100k was a pot so ramp = 5v @ 50 msec. 556 out limited to 200 mA sink.
     
  6. elRey

    Thread Starter Active Member

    Feb 23, 2009
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    Is this MOSFET OK to use for this application?

    http://www.nteinc.com/specs/10to99/pdf/nte66.pdf

    Again, 5v to gate to turn on/off to run a 11-14v solenoid @ 20 - 40 Hz.

    The solenoid currently is powered thru a 10A fuse along with 2 other solenoids. So, it shouldn't draw more than 10A.

    Thanks,
    Rey
     
    Last edited: Sep 10, 2009
  7. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    Why are you running a solenoid at 40Hz? That's pretty fast for a mechanical solenoid and it may simply just stay on or off.
     
  8. elRey

    Thread Starter Active Member

    Feb 23, 2009
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    more than likely 15 - 20 Hz. varying duty.
     
  9. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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    How big is the solenoid?
     
  10. elRey

    Thread Starter Active Member

    Feb 23, 2009
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    I just verified that the solenoid is driven with a 22Hz PWM from the ECU. It's a WG/boost control solenoid for VW/Audi (N75).
     
  11. elRey

    Thread Starter Active Member

    Feb 23, 2009
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    Bernard, are you generating a 20Hz triangle or sawtooth wave with the 556 on the right, then comparing it to the 0-5v from pot on lower left to produce a square wave with desired duty? If so, why is it going back into another 556?

    I'd like more info on your circuit.

    Thanks,
    Rey
     
  12. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    No, you would need a logic level MOSFET. The NTE66 is a standard power MOSFET. You pay quite a bit extra for the NTE convenience vs the prices you pay for the manufacturer parts. NTE doesn't actually make their own components. You can cross-reference other manufacturer's part numbers to NTE parts, but their cross-reference doesn't go the other way.
    The NTE66 is equivalent to an IRF530.
    A logic-level equivalent is an IRL530.
    Usually, you want to use at least double the actual current capacity rating.
    Without knowing more about the requirements, an IRLZ24N, IRLZ34, IRLZ44 should be in the range of what you need.
     
  13. elRey

    Thread Starter Active Member

    Feb 23, 2009
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