The diagram in high and to right represents a preamplifier for alternative signal . The alternative signal present on the basis is amplified , the out is taken on the collector .
The one which is under represents a regulated power supply to continuous tension. The zener diode determines the value of the tension that is present at out .
On left is the diagram of a power supply that transforms a line tension
220 v ~ in a direct tension 12v regulated.
The regulator delivers a precise tension , more it is protected against
overloads and overheats .