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Traic using Microcontroller

gauravkothari23

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Hi all,
i am designing a LED Driver controller using 8051 microcontroller.
i have attached a circuit diagram. i have used N76E003 Controller, and driving a BT131 Traic using controller port pin.
My problem is after a specific NO's of switching (approx 10 to 15 cycles), the triac BT131 stops working, it stays completely ON or stays completely OFF, after replacing with the new one, the things again starts working properly. have also noticed that triac does not get hot,
The load to the triac is only 12 Watts LED Driver. can anybody please let me know, why the triac stops working or gets fused. as it has a very nominal load.
The switching of triac is done using a tactile switch which is not shown in circuit diagram.

am using a non isolated power supply, to power the system.

sometimes have even noticed that it also damages the controller Port PIN
 

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gauravkothari23

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Even i have noticed that connecting a small 220V AC 35 RPM Synchronous Motor works perfectly. it does not damages the Triac.
Then why does the LED Driver with output of 12V 1 Amp damages the Triac
 

KlausST

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Hi,

I don't understand the power supply and how the triac is driven.
I'd expect microcontroller_GND with Neutral.

Klaus
 

paulfjujo

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hello

KlausST said:
I don't understand the power supply and how the triac is driven.
I'd expect microcontroller_GND with Neutral.
i agree with you , neutral must be direct linked to 0V of MCU .
but Check carrefully , if it is really the neutral in your 230V power supply ..
connect the Line instead of Neutral could be mortal !

A Led Driver is not a linear Load .. so final behavior could be very strange if driven trough a Triac..
Did you test it before with a classic incandescence Bulb ie 230V 20 or 40W

take care with 230V AC !! Hazardous situation ..
 

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gauravkothari23

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Thank you all for your reply.
i have made the changes as per Klaust. have connected GND to Neutral.
and the things are working perfect. actually the triac i am using is BT-131 which is rated for 1 Amps, and the problem was due to inrush current when i switch ON the triac, so i added a NTC in series at output of Triac BT-131.
But again i am facing a new problem, where i have to also drive a 220V AC motor and switch it ON and OFF after every 1 seconds for which i am using BT-136 which is rated for 6 Amps.
But the problem is, when i switch ON the Motor, the LED Driver goes OFF Automatically. and when i switch OFF the motor, the LED Driver gets ON again.

Example.
while(1)
{
LED = 1; ON the LED Driver
Motor = 1; ON the Motor;
delay(1000);
Motor = 0; OFF the Motor
delay(1000);
}
So in this case, when the motor is ON LED goes OFF and and when motor goes OFF, the LED gets On Again.
have also attached the circuit diagram.
Have also checked for any shorts, but there are no shorts in PCB.
 

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KlausST

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Hi,

According the schematic the LED_driver is ON when port is HIGH,
But motor is ON when port is LOW.

Klaus
 

gauravkothari23

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Hi,

According the schematic the LED_driver is ON when port is HIGH,
But motor is ON when port is LOW.

Klaus
Yes, the motor stays ON when the port is LOW and LED driver when port is High
--- Updated ---

but i have checked, both the gate Pins of both the triacs. they are not shorted to each other
 

ZASto

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hello



i agree with you , neutral must be direct linked to 0V of MCU .
but Check carrefully , if it is really the neutral in your 230V power supply ..
connect the Line instead of Neutral could be mortal !

A Led Driver is not a linear Load .. so final behavior could be very strange if driven trough a Triac..
Did you test it before with a classic incandescence Bulb ie 230V 20 or 40W

take care with 230V AC !! Hazardous situation ..
Klaus can easily connect line instead of neutral :)
In his country, as well as mine and some other European countries (besides UK and France), you can turn the plug in two ways in socket, as plugs/sockets are not polarized.
Anyway, without proper isolation (1:1 transformer), every circuit connected to mains is potentially lethal. :cool:
 

gauravkothari23

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Hi,

According the schematic the LED_driver is ON when port is HIGH,
But motor is ON when port is LOW.

Klaus
why does the LED driver triac goes OFF when the Motor traic gets ON, even when both gates are not internally connected.
 

gauravkothari23

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What if I run BT 136 triac without moc3021, and directly connecting gate pin to controller port pin
 

KlausST

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Hi,
why does the LED driver triac goes OFF when the Motor traic gets ON, even when both gates are not internally connected.
I can only guess: maybe the supply voltage breaks down

What if I run BT 136 triac without moc3021, and directly connecting gate pin to controller port pin
I asked myself why you used the MOC...please tell us.

Klaus
 

gauravkothari23

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Hi,

I can only guess: maybe the supply voltage breaks down


I asked myself why you used the MOC...please tell us.

Klaus
i used MOC to drive BT136 because i thought that BT136 is not logic level triac.
--- Updated ---

Hi,

I can only guess: maybe the supply voltage breaks down

Klaus
Yes Klaust,
you are right, have added a pull up resistor of 10K on base of BT131 Triac.
the things are working great.
Thanks for the support.
 
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KlausST

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Hi,

I'm not familiar with those triacs.

But had a quick view through the datasheets. Both state on the first page: "direct interface to logic / microcontrollers"
You are an experienced user, so I thought you've read them before.

Even if they do not state this ... gate drive current (and voltage) should be enough of information.

Klaus
 

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