
CHAPTER 27
Power Suppliers
27.1 The Power Required
In the preceding chapters the power supplies needed to make things
work have been assumed. Let us now look at them in detail. Power
for valves and cathode-ray tubes can be divided into three classes:
cathode-heating, anode supplies, and grid bias.
So far as cathode heating is concerned, it is purely a matter of
convenience that it is done electrically. In principle there is no reason
why it could not be done by a bunsen burner or by focusing the sun
on it with a lens. But there are overwhelming practical advantages in
electric heating. Nearly always it is done, for convenience, by a.c.
Cathod ...