hi ppl,
Thank you for your suggestions and ideas.
I brought some new chips on 7805 and retested the circuit.
Let me explain what i did.
I'm using a wall wart with 500 mA output current capacity (as it states on it) with supply of 9V. On measuring its output, it shows 11V. This is given to a dc barrel connector to connect it to bread board. From there the rest of circuitry is same as i had posted earlier. This time, i used 100nF capacitor at both input and output terminals.
I am testing open circuit voltage at output terminal 3 with the same multimeter.
I used a different wall wart this time (again a local made and same ratings). The difference being, this has a bridge rectifier with 1000uF capacitor for filtering.
First i changed the older IC with the same type i.e 7805CT and measured the output across capacitor connected at terminal 3. No change i.e input = output = 11V
Next i changed this IC to another type i.e L7805CV and measured the output across capacitor connected at terminal 3. No change i.e input = output = 11V
Both the times, i'm taking care with the polarity of DC wall wart to bread board and pin connections of 7805.
This is all what i've done.
On checking open circuit voltage using multimeter across terminal 3, should'nt i get 5V? Any ideas?
Btw i have used heat sink for both this time.