Page 138 - Electromechanical Devices and Components Illustrated Sourcebook

100 Electromechanical Devices & Components Illustrated Sourcebook

Magnetic Amplifiers

Clamp Screw Magnetic amplifiers, or saturatable core reactors as they are
sometimes referred to, were first developed in the early 1900s
as an alternative to vacuum tube technology. At this time vac-
uum tubes could not handle particularly high power and were
quite fragile. The magnetic amplifier was extremely tough
and could be built to handle virtually any power level. For this
reason these units found favor in industrial and marine appli-
Washer
cations and were quite common well into the 1990s. High-
power transistor technologies have replaced most magnetic
amplifier applications, however, in extreme conditions these
units are still used. One area where magnet amplifiers are still
Upper Core used with great effect, is as extremely high-current regulated
power supplies.
Figure 5-66 shows a basic magnetic amplifier schematic.
The unit is an iron-core inductor with an additional reactor
Coil Form coil. The input signal is used to manipulate the level of core
saturation and, in turn, the resistance of the inductor. Figure 5-67
shows a typical commercial magnetic amplifier. Notice the
Coil
similarity in appearance to a saturateable core transformer.
Terminal Wires
Magnetic Recording Devices

Magnetic recording technologies play an important role in our
Lower Core
day-to-day lives. Most notably as the little magnetic strips on
the back of our credit cards and the hard drives in our com-
puters. Although digital technologies have displaced most
Wire Slots
magnetic recording systems, most of us have had dealings
Washer with either video or audio cassette decks in our lives.
Magnetic recording was invented by Valdemar Poulsen, in
1898. Considering the impact that magnetic recording has had
Nut
on society, it seems a shame that this man doesn’t occupy a
Figure 5-64 Exploded View of a Ferrite Core Inductor with noteworthy position in the history of technology. Rather, he
Toroidal Frame has slipped into obscurity and, with the exception of his occa-
sional mention in texts such as this one, his name is com-
pletely unknown.

Output

Power Supply
Inductor Coil
Schematic Symbol Core
Coil
Nose
Coil
Form
Input
Adjustment
Screw
Moving
Core Reactor Coil
Figure 5-65 Moving Core Inductor Figure 5-66 Magnetic Amplifier Schematic