Triac as a switch using MOC3041

[DatsAbk]

Hello,
I have made the following circuit


The problem I'm facing is that when I switch off or switch on the AC supply,a momentary flash is generated in the load(CFL)

The triac is snubberless and even then I'm facing this problem.What is the possible solution to this?

 

[cntube]

Try adding capacitor across Ra1 to filter high dv/dt transients caused by switch closings.

 

[emontllo]

Totally agree with cntube. Although branded as "snubberless" an snubber may be also useful depending on circuit inductance and behaviour...

 

[mohammed idris]

I am facing similar problem while controlling A.C Load using MOC3041 and Triac BTA12. Everything is fine, until when i make any movement with the plugs on the extension unit from where i have given the 230 V A.C Supply to Microcontroller as well as Load. The load gets on, even where there is no input from microcontroller and gets off in a secs on any movement of plugs on the extension sockets . This unwanted switching of load is risky in my apllication. plz advice

 

[ruhulamineee]

Okay this can be happened due to circuit reactance.
Nothing to be worried about that you just try to find free line to discharge the reactive element when switch off.

 

[mohammed idris]

Okay this can be happened due to circuit reactance.
Nothing to be worried about that you just try to find free line to discharge the reactive element when switch off.

Sir, Can you please go through my circuit and suggest any modification .
/***************************************************************************************************************/


https://obrazki.elektroda.pl/5894779500_1360835298.jpg
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Or Refer the attachment.
Plz advice. Waiting for you response

 

[picgak]

1 capacitor resistor in series should be bettween A1 A2 of Triac in the above cct it is wrong.
2 Make sure that 390R is Good
3 Make sure that 390R is bettween A1 and Gate

 

[mohammed idris]

1 capacitor resistor in series should be bettween A1 A2 of Triac in the above cct it is wrong.
2 Make sure that 390R is Good
3 Make sure that 390R is bettween A1 and Gate

Thanks for the input.
Yes i have make sure the 390R's are fine.

Also the Snubber n/w of resistor and capacitor is b/w A1 and A2 of Triac. I have attached the rectified diagram, I had drawn the load at wrong place in last diagram.

Plz advice, as i still face the same problem earlier

 

[picgak]

Now switch on the circuit without the input of opto connected to the micro cct. if it is ok then your circuit is ok
please check

 

[pplus]

Because of the switch contact bounce generated a momentary flash.

 

[mohammed idris]

Now switch on the circuit without the input of opto connected to the micro cct. if it is ok then your circuit is ok
please check

Thanks for the reply again.

I disconnected the supply of microcontroller section only and kept the supply ON to the Triac A.C load section. This time there was no switching ON-OFF of A.C loads on making movements of plug on extension socket as opposed to as earlier observaton. So, is it ok, or should i cut the track of input to opto-coupler from micro ckt.
Plz advice, if i have done the right testing as per your advice and as ther were no On-OFF of load on movement of A.C plug, whether the ckt is now full proof.

plz advice.

 

[sam781]

TRIAC triggering circuit is slightly different in TI's MOC3021's data sheet. MOC3021 is random phase triac driver optoisolator where 3041 is zero-cross opto.

Another query is - what is the difference between sensitive gate and non sensitive Gate TRIAC?

 

[sam781]

Actually I wanted to know why circuits are different for zero cross TRIAC driver and random phase TRIAC driver. It it really required to connect A2 and Gate with a resistor? If yes, why?

 

[nikhilt007]

Actually I wanted to know why circuits are different for zero cross TRIAC driver and random phase TRIAC driver. It it really required to connect A2 and Gate with a resistor? If yes, why?

moc3041 contain inbuilt zero crossing detection circuit
when you are using these dont use zerocrossing detection using microcontroller
i suggested here to use moc3021 that will work better

 

[sam781]

moc3041 contain inbuilt zero crossing detection circuit
when you are using these dont use zerocrossing detection using microcontroller

As per my understanding, even zero cross TRIAC driver (e.g, MOC304X) is used; zero crossing cricuit is required for the MCU to know when the power line's zero corss happen. Based on this zero cross MCU will trigger the TRIAC.

 

[picgak]

Thanks for the reply again.

I disconnected the supply of microcontroller section only and kept the supply ON to the Triac A.C load section. This time there was no switching ON-OFF of A.C loads on making movements of plug on extension socket as opposed to as earlier observaton. So, is it ok, or should i cut the track of input to opto-coupler from micro ckt.
Plz advice, if i have done the right testing as per your advice and as ther were no On-OFF of load on movement of A.C plug, whether the ckt is now full proof.

plz advice.

So from the check we have done your opto and power side circuit is working Fine

Now the problem is in your opto switching circuit
when the micro circuit is powered on first some pulse is going to the opto instantly that is were the problem is.

Now
1 are you giving pulse directly from the micro to the opto
2 positive pulse from the micro should directly be given to the opto if any inverting stage is used this problem can happen