Ok, I have a bit a problem! I often got transistors marked lik C1203 or similar D1216. So is there a way I can know if there are BC or BD equivalents or SC and SD!?
You can google for a data sheet. I just googled 'C1203 data' and the first link took me to alldatasheet dot com. I had to look around there to find the right data sheet. If you manage to find the correct sheet, you can look at the specs and come up with a substitute.