Problem With 220 VAC Halogen Lamp Dimming


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  1. #1
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    Default Problem With 220 VAC Halogen Lamp Dimming

    I was using Pic based Zero Cross Detect dimmer Incandescent lamps with no problem.
    However; when i use halogen lamps instead of incandescent lamps, The dimmer circuit isn't working properly.

    So, what seems to be the problem? Any sudgestions?

    Regards..

  2. #2
    Join Date
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    Default Re: Problem With 220 VAC Halogen Lamp Dimming

    i would check the rating of the switching mosfet , as some halogen can have a higher load current at startup than incandescent lamps

  3. #3
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    Default Re: Problem With 220 VAC Halogen Lamp Dimming

    I have used Opto-Triac and triac for dimming A.C halogen lamp.

  4. #4
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    Default Re: Problem With 220 VAC Halogen Lamp Dimming

    You need to post the schematic and the code, if you want some real help.

    Cheers

    Al.
    All progress began with an idea

  5. #5
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    Default Re: Problem With 220 VAC Halogen Lamp Dimming

    Having looked into Halogen lamps I noticed that there are Dimmable versions and was wondering what can be the difference between standard Halogen lamps and dimmable Halogen lamps?

  6. #6
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    Default Re: Problem With 220 VAC Halogen Lamp Dimming

    Quote Originally Posted by aratti View Post
    You need to post the schematic and the code, if you want some real help.

    Cheers

    Al.
    Hi aratti,

    This is the test code that i have used always for many projects. The microcontroller is PIC16F876A. PORTB.0 is Zero Cross Detect Input. PORTB.7 is fire triac output.

    Code:
    INCLUDE "DT_INTS-14.bas"     ' Base Interrupt System
    
        
        TRIAC       VAR PORTB.7
        
        TIMEX       VAR WORD
        TIMEX_L     VAR TIMEX.LOWBYTE
        TIMEX_H     VAR TIMEX.HIGHBYTE
    
        OUTPUT  TRIAC
        INPUT   PORTB.0
        
        TRISC   = 255
        TRISA   = %111111
        
        
        ADCON1  = 7
        
        T1CON = 0
        CCP1CON = %00001010
        TMR1L   = 0
        TMR1H   = 0
        OPTION_REG  = %11000000
        
        
        FLAG  = 0
        TIMEX = 9000
        
        CCPR1L      = TIMEX.LOWBYTE
        CCPR1H      = TIMEX.HIGHBYTE
        
        
        LOW TRIAC
        
        
        PAUSE 100
        
        ASM
    INT_LIST  macro    ; IntSource,        Label,  Type, ResetFlag?
        INT_Handler   INT_INT  ,  INT_GEL_1,   ASM,  yes
        INT_Handler   CCP1_INT   ,  INT_GEL_2,   ASM,  yes
            ;INT_Handler   TMR0_INT  ,  TMR0INT,   ASM,  yes
        endm
        INT_CREATE               
        ENDASM
    
    @ INT_ENABLE  INT_INT
    @ INT_ENABLE  CCP1_INT
    
       MAIN :
        
        
        
        TIMEX = TIMEX + 1
        
        
        IF TIMEX >= 9600 THEN
            FLAG = 0
            low TRIAC
        ELSE
            FLAG = 1
        ENDIF
        
        PAUSE 1
    
    
        
        GOTO MAIN
        
        ASM
    INT_GEL_1
        
        BCF _TRIAC
        BSF T1CON,0
        
        INT_RETURN 
        ENDASM
        
        ASM
    INT_GEL_2
        
        BTFSC _FLAG , 0
        BSF _TRIAC
        BCF T1CON , 0
        CLRF TMR1H
        CLRF TMR1L
        
        
        
        MOVF    _TIMEX_H , W
        MOVWF   CCPR1H
        
        MOVF    _TIMEX_L , W
        MOVWF   CCPR1L
        
         
        
        INT_RETURN 
        ENDASM
    
    END

  7. #7
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    Default Re: Problem With 220 VAC Halogen Lamp Dimming

    Hi,

    I noticed a little funny thing while building a dimmer ...

    take care to the input port behaviour vs input ( TTL or ST ? ) AND the applied rectified voltage ...
    the zero detection can occur very, very late from what is expected ...

    scoping what happens is very interessing.

    I solved it using the falling edge detection and applying a small delay leading precisely to the very beginning of the rising edge - 'scope used here -.

    so, the zero detection is very precise.
    ( application is a 250W IR Lamp for heating my hens home ... )

    Alain
    Last edited by Acetronics2; - 5th August 2014 at 16:21.
    ************************************************** ***********************
    Why insist on using 32 Bits when you're not even able to deal with the first 8 ones ??? ehhhhhh ...
    ************************************************** ***********************
    IF there is the word "Problem" in your question ...
    certainly the answer is " RTFM " or " RTFDataSheet " !!!
    *****************************************

  8. #8
    Join Date
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    Default Re: Problem With 220 VAC Halogen Lamp Dimming

    Thanks Alain and other friends for your replies..

    The problem was solved with a small R-C snubber. Connected to A1 and A2 pins of Triac.

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