Thank you for correcting me about the values of those two resistors.

Figure the maximum power that you can dissipate with 240 VAC and 94 k Ohms. Subjectively, from your description of the damage there was a whole lot more power involved.

There would have been a couple milliamps going through the optical coupler. How can a couple milliamps at a couple of volts cause that kind of destruction?

My only conclusion is that either some wrong parts were used or the circuit was not faithfully followed.

You mentioned that you "...built that on a breadboard..." If it was one of those plastic plug-in breadboard might be that is part of the problem. Does it have a voltage rating? Maybe the connections on it are not what you expect -could be the result of a defect.

Maybe you would find that buzzing out the connections i nthat part of the circuit to be a profitable exercise. Then barring some kind of high voltage breakdown you will be able to separate problems with continuity from problems with components.

Not intending to argue, just trying to help you think about this..

 

Thank you for correcting me about the values of those two resistors.

Figure the maximum power that you can dissipate with 240 VAC and 94 k Ohms. Subjectively, from your description of the damage there was a whole lot more power involved.

There would have been a couple milliamps going through the optical coupler. How can a couple milliamps at a couple of volts cause that kind of destruction?

My only conclusion is that either some wrong parts were used or the circuit was not faithfully followed.

You mentioned that you "...built that on a breadboard..." If it was one of those plastic plug-in breadboard might be that is part of the problem. Does it have a voltage rating? Maybe the connections on it are not what you expect -could be the result of a defect.

Maybe you would find that buzzing out the connections i nthat part of the circuit to be a profitable exercise. Then barring some kind of high voltage breakdown you will be able to separate problems with continuity from problems with components.

Not intending to argue, just trying to help you think about this..

No offense taken sir, you are trying to help me. I appreciate it.

When I calculate the power rating needed for the resistors I come up with a power rating of a little more than 0,6 Watts for both resistors. Can I just divide that by 2? Do I have the power rating for 1 resistor then?

Yeah the breadboard might've not been the best option. The author of the link Max sent did the exact same thing, also in a breadboard so I figured it was possible.

So now that we basically checked everything the conclusion must be that I did not build it correctly. Im going to try and build it again.

What do you mean with buzzing out the connectors? If you mean to put the points where 230V are connected not in the breadboard, thats what I did. I wired the 230 cable on the load, triac and the resistors. Then I put the resistors in the breadboard.

Again I do not see this as argueing. I really appreciate your help.

 

(Some text removed for clarity)

When I calculate the power rating needed for the resistors I come up with a power rating of a little more than 0,6 Watts for both resistors. Can I just divide that by 2? Do I have the power rating for 1 resistor then?

Yes. Simplifying assumptions I used is that if connected correctly there will only be a couple of volts across the LED on the optoisolator, and the resistors will share power equally. So each resistor will see (240V/96k)/2 = 0.6W/2, same as you came up with.

(Some text removed for clarity)

So now that we basically checked everything the conclusion must be that I did not build it correctly. Im going to try and build it again.

What do you mean with buzzing out the connectors?

By "buzz out" I mean to take a battery and a buzzer (or a modern day DVM that sounds a tone when a connection is tested) to check the connections between the component leads.

Since there are only four components on the Line side of this part of the circuit this should be easy to figure out. -Let's check one other thing: Do you have any test equipment connected when power was applied? If so, how was it connected.?

 

Yes. Simplifying assumptions I used is that if connected correctly there will only be a couple of volts across the LED on the optoisolator, and the resistors will share power equally. So each resistor will see (240V/96k)/2 = 0.6W/2, same as you came up with.



By "buzz out" I mean to take a battery and a buzzer (or a modern day DVM that sounds a tone when a connection is tested) to check the connections between the component leads.

Since there are only four components on the Line side of this part of the circuit this should be easy to figure out. -Let's check one other thing: Do you have any test equipment connected when power was applied? If so, how was it connected.?

Okay, so here's what I am going to do. I used the buzz out method to build the circuit again and I checked it again. Today I will test it again, but this time I will test it on low voltage first. Using a frequency generator. Then after that worked, I'm just gonna go ahead and try it on 230 Vac again.

I'll let you know what happens.

I didn't have any test equipment on when I tried it the first time no.

Thanks so far and thanks in advance guys!

 

(Waiting in breathless anticipation of the news...)

 

(Waiting in breathless anticipation of the news...)

Haha hello again.

Sorry sir I don't do anything during weekends, I just dont have the time.
What I said I would do I did partly. I have tried the zero-cross detection circuit with a frequency generator and oscilloscope and eveything and it worked like a charm. So what I am going to do this afternoon is the following.
I will try to do the same thing with 230 Vac with the correct resistors. I think I have some good ones lying around.

I will keep you posted on how that went. Probably tell you tomorrow.

ZweedNaat

 

Okay, so. As promissed I'm gonna tell you what happened...

And I am happy to announce that the circuit works. Since only the zero-cross detection blew up I went ahead and only made that part of the circuit again. This time I decided to put 2 18k resistors in. Both can handle 7W of power so it should be enough. Also the value of the current flowing to the opto is not too high (230/(2*18000)= 6.39 mA, which is a little below the typical value of 10 for the chip).

Then I went ahead and put the arduino on. And appearently I can detect zero-crossings now.
What I will do next is the following. I will make the dimmer circuit and go ahead and put that on and use the code from the link earlier (http://alfadex.com/2014/02/dimming-230v-ac-with-arduino-2/).

I noticed one thing tho. In the code the author uses delay's in a interrupt funtion. Isn't that kind of bad? Seems to me it wouldn't work because the interrupt it self uses the same mechanism.

Well, I'll keep you updated after I put the dimming in.

 

What is the maximum power in your 7 watt resistors? (That is a rhetorical question)

Glad to see that you have it up and running!

I think in this case a delay following the interrupt is one good way to fire the triac at the proper phase.

 

What is the maximum power in your 7 watt resistors? (That is a rhetorical question)

Glad to see that you have it up and running!

I think in this case a delay following the interrupt is one good way to fire the triac at the proper phase.

Thank you sir!

I really appreciated all your help and the help of other involved people!

Thank you all have a good day!