Learning Event 6:
DESCRIBE THE PURPOSE AND USE OF MAGNETIC HEADS
1.
Magnetic heads. No assembly in a magnetic recording system is more important
than the heads. These convert the electrical current to a magnetizing force during
the record operations, and convert the magnetizing force to an electrical current
during playback.
a. If a core of permeable material is inserted within a coil of wire with
direct current running through it, a magnetic field is set up that will influence
any nearby material that is capable of being magnetized.
b. In the record head, alternating current is used. This is not sine wave AC
but current, which is varying in amplitude, and frequency, to conform with a
person's voice or music.
c. The core (item 1, fig 1-10) is shaped like an incomplete ring.
The
discontinuity forms the gap (item 3, fig 1-10) which is inserted in a coil (item 2,
fig 1-10) of wire.
d. When the signal to be recorded is converted to an electric current and
passed through the coil, a strong magnetic field is created across the gap.
Figure 1-10.
Record head
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