||28,500yen(around the 1972 time)
|32,500yen(around the 1973 time)
The belt drive phone motor which adopted DC servo
The brushless motor to which Pioneer applied the hall device
which developed the process is adopted as a motor.
The drive magnetic field of this motor is made by the electric current from the transistor circuit committed by switching of a hall device. The attraction-of-magnet transition to a hall device was regularly performed one by one by the magnet rotor magnetized beforehand, and has obtained the exact rotation.
Moreover, since it is a low-speed motor which rotates by a 10 times as
much speed as a turntable, there is little oscillation and S/N and the
endurance are improving.
Even if DC
servo mechanism is carried and rotation deflection arises, a drive voltage is
made to control and an exact rotation is maintained.
This servo mechanism
consists of a capacitor type rotational frequency detector which does not
receive the influence by a transition of ambient temperature, or the attraction
of magnet of a rotor magnet, and an electronics control circuitry,The method
detector of a capacitor changed the deflection of the rotational frequency into
the transition of the frequency of oscillation as it was, and the electronics
control circuitry has controlled the drive voltage according to the transition.
The pure electronic formula is adopted as a rotational frequency switching,
and since need to hang a belt and it is not necessary to change it like
before, there is no trouble resulting from a belt or its switching organization.
Moreover, 33 The fine-tune thumb which became independent to 1/3.45rpm each
is carried, and the coordination of the rotational frequency is enabled by ±2%
of within the limits.
||Brushless DC servo hall motor
||Diameter aluminum alloy die-casting of 31cm
||33 1 / 3 or 45rpm, a fine-tune possible
|Rotational frequency adjustable range
||Less than ±2%, an each rotational frequency
|Rotational frequency switching
||0.05% or less (WRMS)
||55dB or more
|An attached organization
||Rotational frequency fine-tune knob
|The semiconductor used
||Transistor: 22 pieces
Diode: 15 pieces
IC: One piece
Hall device: Two pieces
||Width 317x height 133x depth of 353mm