I wasnt saying you should order from Rapid. They are my first choice though. Other electronics suppliers will have a page for relays too. I have been buying quite a few of their own components and i cant say ive had a single problem with any of them. When i need to use a new type of component i usually buy a few different versions that appear to do the same thing and test them. If by "78L05" you mean "7805 voltage regulator" then i have been using those for a long time now and theyve always been fine. Ive only had 1 or 2 beak but that was my fault for shorting it out and not realising till i touched them. I think one actually still works after burning my finger.

Heres a wikipedia page on triacs. Ill post back soon with a scematic and description. Also that page says the mains pins are A1 and A2 not A and B as i said before.