Dimmer

[Reven]

This is the osciloscope measures from the GP4 (AcLine input), and from GP2 (Output to TRIAC).
I use tranformer 8Vac, R3=4k7 and R4=10k.

Look the pictures from 0 to 4. Is from value off to on through 3 steps.


But the lamp still flashing...

[HenrikOlsson]

Reven,
I've not used that circuit or code you are reffering to but by just looking at your waveforms it seems that the triac is triggered at the same phase angle in case 1, 2, 3 & 4.

The triac only needs a short pulse on the gate and will then hold itself 'on' untill the AC-line crosses zero, at which point it will turn 'off'. That short pulse should be delayed a certain amount of time from the zero crossing.

On your scope pics the triac seems to be triggered exactly 1div from the zero crossing in all cases except full on and full off.

/Henrik Olsson.

[Acetronics2]

Hi, reven

Henrik is right ...

Here, the pulse length is not the thing to be variable.

but you must vary the time between zero voltage detection and triac gate firing ...

Long time = weak light
short time = full light

remember once the triac is turned on it stays turned ON until current becomes null.


Alain

Here, you had programmed a ... DC Dimmer !!!

[Reven]

I think you have right...
As Henrik says ,now the triac is triggered at the same phase angle in all cases.
I must change my code to put the pulse position in a variable.
Thanks all of you!
I will inform you about my progress!




BTW, take a look at the code,bacause I checked it many times and I could not find where the problem is.

http://www.picbasic.co.uk/forum/atta...0&d=1103787743

Thanks again,
Reven

[Acetronics2]

Hi, Reven

Just understand what the interrupt routine does instead of should have done ...

""
' ACDetect
' --------
'
' Interrupt routine called by ACLine (GP4) pin state change
'
disable
ACDetect:
if ACline==1 then ' Check for rising edge of AC signal
if triacdelay > 0 then
Triac=1 ' Activate TRIAC

Alain's : ;;; No,No,No ... here we have to wait for ( Maxdelay - Triacdelay ) !!! THEN fire the Triac for, say, 20µs ... then let things quiet.

if FullBright==0 then ' In case Brightness flag is not set
pauseus triacdelay ' do the selected delay
triac=0 ' Disable TRIAC
endif
else
triac=0
endif
endif
INTCON.0=0 ' Clear GPIF (interrupt on GP4 change)
resume
enable

""


*** This part of program smells to have been taken from a heather using burst mode dimming ...

Sorry, Steve ... je t'aimais bien ( avec la musique de circonstance ... )

Alain

[mister_e]

mmm, sorry all. something should be wrong in what i posted. I used that program in various app and it worked... let me the time to return at home(Next week) and i'll compare the posted version and what i use...

Many thousands of appologies.

[mister_e]

Can't wait to return home... use the following ACDetect routine instead.
this should work.

disable
ACDetect:
if ACline==1 then 
    '
    '    Rising edge of AC signal
    '    ========================
	if triacdelay then              ' A delay is set by user
                                        '  
	    if FullBright==0 then       ' Full Brightness flag is not set
            pauseus maxdelay-triacdelay '    do the selected delay
            triac=1                     '    enable TRIAC	    	
            else                        '
    	        triac=1                 ' Full Brightness flag is set
                                        '    enable triac
            endif                       '
                                        '
        else                            '
    	    triac=0                     ' No Delay set by user... disable Triac
        endif                           '
    
    else                                
    '
    '    Falling edge of AC signal
    '    =========================
        if fullbright==0 then triac=0   ' Disable the Triac on falling edge of 
                                        ' Ac signal
    endif
INTCON.0=0 ' Clear GPIF (interrupt on GP4 change)
resume
enable

Yeah i know you can also use Pulsout and forget the Falling edge detection... as you wish. Both will work.