little phase control to 135º

Discussion in 'The Projects Forum' started by silvajq, Apr 14, 2010.

  1. silvajq

    Thread Starter New Member

    Apr 14, 2010
    7
    0
    Hello everybody,
    I have proble, i wan to build a phase control to control my output from 0º to 180º. i just search for everywere, and i jus tmade one to control for example a lamp. but now i have a new project, my supplie AC voltage is about 5VAC, and i want to control the phase with this value, for a maximum out put of 1amp. i hust try with TCA 185 and so on and i'm not able to put it working, can someone give a litle help?
    I'm new member, i just take a look to forum and it is fantastic!
    Regards,
    Silva
     
  2. t06afre

    AAC Fanatic!

    May 11, 2009
    5,939
    1,222
    Have you tried to use the all-pass filter. You will find info about on wiki. I have never used it my self so I do not know how useful it is as a design element
    Edit: This is perhaps not that the OP had in mind. I think I misunderstood the request. Sorry for that
     
    Last edited: Apr 14, 2010
  3. DickCappels

    Moderator

    Aug 21, 2008
    2,647
    632
    A couple of ideas spring to mind. The simplest from a conceptual point of view is to use a monostable multivibrator that triggers at the zero crossing and triggers you triac of SCR a time later. Simpler still, but more direct is to use a two pol RC circuit to delay the rise in the trigger voltage.

    If you post the circuit you are now working with, i am sure you can get more speicific answers.
     
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  4. rjenkins

    AAC Fanatic!

    Nov 6, 2005
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    69
    Have a look at a Programmable Unijuntion Transistor like 2N6027.

    With a few components you can make good phase control dimmer.

    Have a look at figure three in the datasheet.
    http://www.onsemi.com/pub_link/Collateral/2N6027-D.PDF

    Change the 510K fixed resistor to a 1K plus a 470K pot and make Cc about 0.1uF?? Cant remember the ideal value.

    Feed the circuit from full-wave rectified but *unsmoothed* 12V.

    If you use a 12V center tapped transformer you can use the center tap for a lower voltage supply to your lamp? and the other side of the lamp to the anode of a small thyristor.

    Connect the thyristor cathode to timing circuit negative and the gate to the top of the 20 Ohm resistor via a 10 ohm.
     
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  5. silvajq

    Thread Starter New Member

    Apr 14, 2010
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    i try with two different circuits, that you can see in the atachments, but they are all for a 230vac inputs, and i want to do it for at maximum 12vac. i just simulate the 2 circuits on the multsim with 12vac and with all components with exact value and it works fine :) but when i assembly it on pcb board, the circuit didn't work! on the first circuit i switch the diac to one diod 1n4007

    Silva
     
    Last edited: Apr 15, 2010
  6. silvajq

    Thread Starter New Member

    Apr 14, 2010
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    0
    Sorry Robert,

    I don't understand what you mean on your last paragraph "Connect the thyristor cathode to timing circuit negative and the gate to the top of the 20 Ohm resistor via a 10 ohm"

    Silva
     
  7. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
    102
    @Silva,

    Try the following component changes to see if the the IC works. I have not tested it so good luck for the trial.

    [​IMG]
     
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  8. silvajq

    Thread Starter New Member

    Apr 14, 2010
    7
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    Hi,

    Didn't work, in my opinnion all the components are prepared for a imput of 230vac, and this way will no work :,(
     
  9. eblc1388

    Senior Member

    Nov 28, 2008
    1,542
    102
    Please measure voltage across 470uF 16V capacitor and post back.
     
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  10. rjenkins

    AAC Fanatic!

    Nov 6, 2005
    1,015
    69
    Figure three in that data sheet has a circuit with the output across a 20 Ohm resistor.

    That would be where to to connect to a thyristor, with the gate via a 10 Ohm resistor to limit the current.
     
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  11. silvajq

    Thread Starter New Member

    Apr 14, 2010
    7
    0
    Hello, sorry my delay, but i was on holidays, so finally the circuit is running (with the TCA), the problem was in my test board!! she had some contacts broken!

    I want to thank you and to the other users that help me!

    Silva
     
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