1445326735900-0

Starting electronics
You should remember that the rate at which a capacitor
discharges is dependent on the value of the capacitor. So, to
make sure the stored voltage doesn’t fall too far in the time
between the peaks of the half cycles, the capacitor should
be large enough (typically of the value of thousands of microfarads)
to store enough charge to prevent this happening.
Nevertheless a variation in voltage will always occur, and the
extent of this variation is known as the ripple voltage, shown
in Figure 7.13. Ripple voltages of the order of a volt or so are
common, superimposed on the required d.c. voltage, for this
type of circuit.
Figure 7.13
ripple voltage
The extent to which the d.c. is not exactly linear is known as the
Stability built in
The power supplies we’ve seen so far are simple but they do
have the drawback that output voltage is never exact — ripple
voltage and to a large extent, load current requirements mean
that a variation in voltage will always occur. In many practical
applications such supplies are adequate, but some applications
require a much more stable power supply voltage.
160