AC lamp dimmer circuit?

[Don_dody]

I'm sorry, I really don't know. I think I never change the default setting.
I use crystal 12 MHz for the minimum system.

 

[Don_dody]

Hi, I just change the clock to 12MHz and this is the result.
Is it correct ??

 

[Tahmid]

Yes, it's correct.

Time/div is 2ms/div.

The zero crossing signals are spaced 5 divisions apart, so 10ms apart.
The width of the generated pulse (in blue) is 1 division wide, so 2ms. This is what you require.

So, it's the correct result. :smile:

 

[Don_dody]

:smile:
Thank you very much Tahmid, You help me a lot.

Next, go back to the main point.
I want to dim 3 AC lamps, with different intensity. So, is it enough to use only one ZCD circuit ?
and then what is the relation between ZCD with AC dimmer circuit ?

 

[Tahmid]

You can use phase angle control. For that, you need to fire the triac at a specific time after the zero-cross. The longer you wait before firing, the lower the brightness. And vice versa.

Since all 3 lamps will be driven from the same source, one zero-cross detection circuit is enough.

 

[Don_dody]

For that, you need to fire the triac at a specific time after the zero-cross.

Is there any regulation for that specific time or minimum and maximum time to fire the Triac ??

 

[Tahmid]

The time after which you fire will determine the output.

The duration to keep the triac on will depend on your drive current in the triac firing circuitry.

 

[Don_dody]

Hi, I understand the concept of ZCD and Phase Firing Angle already, but somehow I just did not yet find a way to implement the concept into the code since I'm not so good in programming.

Can you guide me to generate code to control the TRIAC firing if I connect the circuit to PORTB1 of ATmega8535 ?
Is it using delay, interrupt, or what?
I'm using codevisionAVR.

 

[Don_dody]

Hi I just try to make it and this is my code:

#include <mega8535.h>
#include <delay.h>

interrupt [EXT_INT0] void ext_int0_isr(void)
{
    PORTD=0x02;     // Output delay
    delay_ms(2);
    PORTD=0x00;
}


void main(void)
{
    DDRD=0x02;      // PORTD pin1 as output
    DDRB=0x01;      // PORTB pin0 as TRIAC input (MCU output)
    
    GICR|=0x40;     // Interrupt at PORTD pin2
    MCUCR=0x01;
    MCUCSR=0x00;
    GIFR=0x40;


#asm("sei")

PORTB = 0X01;       // initially triacs off

while(1)
{
while(PORTD.2 == 1) // zero crossing detected
{
PORTB = 0x01;
delay_us(500);
PORTB =0x00;
}
while(PORTD.2 == 0) // half cycle of ac reached
{
PORTB = 0x01;
delay_us(500);
PORTB = 0x00;
}
}
}

and here is the circuit:



Proteus simulation says time step too small and error.
Can you tell me what's wrong here?

Before I connect the dimmer circuit, everything is OK, but when it is connected -> ERROR.
This is what I got before dimmer is connected



Is it correct???

 

[kurasu]

nice circuit but i don't understand with Cde pin must connect to pin no at pic ? can u help tell me .. thanks...