AC to DC

Discussion in 'General Electronics Chat' started by ols1570, May 19, 2014.

  1. ols1570

    Thread Starter New Member

    Dec 3, 2013
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    0
    Hello everyone

    I have a source 650V 1.2A 50Hz. Half bridge. I want to make it full DC straight line with capacitors filter. Any idea how to make it?

    Thank you
     
  2. wmodavis

    Well-Known Member

    Oct 23, 2010
    737
    150
    Add a capacitor across the output of the rectifier.
     
    ols1570 likes this.
  3. ols1570

    Thread Starter New Member

    Dec 3, 2013
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    0
    But what kind of capacitor? I need the parameters please
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,571
    2,381
    Ensure the correct PIV for the rectifier and capacitor value is correct if the actual DC is 650V.
    Max.
     
  5. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,813
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    This all sounds horribly dangerous if you're messing with 650V and are having to ask these questions. Is your source 650V AC (rms) or DC? Is it isolated?
     
  6. wmodavis

    Well-Known Member

    Oct 23, 2010
    737
    150
    You have NOT specified enough information to guesstimate all of the specifications for a filter capacitor. For instance...
    1. What is the load current?
    2. What is an acceptable amount of ripple?
    3. Is the source voltage given in RMS or peak?

    I will tell you it will be near impossible to have "full DC straight line" (whatever that is - I can only guess what you really mean) if you have any load.
     
  7. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    Without any load just about any capacitor will make a "straight line" voltage, with just a bit of variation due to the leakage of the cap itself, and some more due to the measurement device itself.

    If you draw any current at all you need to jump to an infinite cap to see the same stellar straight line.

    Sorry, that's the physics mate. To make a straight line with load you need post regulation, some circuit that will regulate to some lower voltage then the maximum or even minimum voltage of the cap.
     
  8. ols1570

    Thread Starter New Member

    Dec 3, 2013
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    0
    I ve a strange thing here when the system. When i put the load the voltage get 0 Volts.
     
  9. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    That sounds much safer ;)
     
    ErnieM likes this.
  10. wayneh

    Expert

    Sep 9, 2010
    12,156
    3,063
    I don't see how this thread is not about a "transformer-less power supply". Maybe it would get closed faster if he said he was doing it in his car.
     
  11. Mike33

    AAC Fanatic!

    Feb 4, 2005
    349
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    I used to get zero volts, too, when I'd put a 10 ohm resistor on a 5 volt transformer meant to output something like 50mA ;)

    Seems there is much more to learn, OLS! Take it one step at a time, and not at high voltages, please....
     
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