Thank you all.
1. I dont understeand why the voltage on inverting input should be the same with the one on the non inverting input. Sorry - this is the ideal summing point condition.
2.Unfortunately i dont have a scope, also i didnt place the ammeter on my board. Are u taliking about the oscilations from the transformer ? If thats the case than i tested it with a 12 V regulated power supply.
Now correct me if i am wrong: (i am a beginner and i try to combine practice with theory)
In this circuit on pin six i must have a potential of 7.15 V (from datasheet). By placing a variable resistor between pin 6 and 5 i modify the potential of pin 5 from 0 to 100% of pin 6 potential. Now, this is an noninverting op. amplifier (this circuit) which means the voltage meassured between ground and the emitor is :voltage on pin 5 multiplied by (1+(R4/R5)).