@Vitaly
Thx for your quickly answer! I've build some seriell Interface's but your schematic looks not so easy! I'am not an electrican, it's my hobby! If I buy the microprocessor, how get I the firmware on it, or are that not needed? You see, I don't know many things! And my english is to bad, to understand all points.
What a NPN TRANSISTOR is, I know. What is beta 100?
Hope you understand my very bad english, but to learn it, in school was boring! *gg*