I don,t understand my problem. i builded a new circuit with new parts, same problem. The optocoupler has 5v like in your shematic. I get a signal for the zerocross detection out of the circuit, 100Hz like it should be (Why 21V I don't know, but it looks like it should). I made a screenshot with the phone of the oszi and attached it.
Then I looked at the firing pulse. Here comes something out, but with a different frequency.some peeks are missing.
Then I looked at the output of the triac A1. There comes rubish out. I attached a screenshot. The picture you are seeing variates, it looks as if it is walking (like a rising, as if timing is growing).
Perhaps you can have a look at it and can support me.
I tried to send this post, but I cant compress the pictueres to the max allowed size. Is there an other way to send it to you?
Thanks in advanced.