I am learning electronics. Today I tried using 7805 and 7809 voltage regulators with a 12V battery.
Though my battery is of 12V, currently it has 8.76V in it.
In my first attempt, I connected a 7805 with the battery and I got ~ 8.70V in the input terminal and in the output terminal I got ~ 4.98V which is pretty obvious.
The unexpected things happened when I connected the battery with a 7809 voltage regulator.
Here in the input terminal, I got ~ 8.69V, but in the output terminal I got ~ 7.91V.
Now this is pretty unusual to me because I am using a 9V voltage regulator and if I assume that due to the internal resistance of the wire, I am losing around ~ 0.2V then for 7809 the output reading should be ~ 8.67V.
Where is the unsolved (8.67-7.91=) 0.76V? Why isn't this the case with the 7805?