Nor265 User Guide
Norsonic AS
29
10 Technical design
The figure below shows a block-diagram of the microphone
boom/turntable
N o r 2 6 5
.
The motor is a stepper motor designed for continuous movement
(micro-stepping). A digital signal processor controls the position of
the motor shaft directly with a very high resolution. Since the systems
apply no feedback, the system will never generate the type of noise
often found in feedback system due to play resulting from wear in the
drive system.
The motor is powered all the time, even at rest, and will therefore
need no braking action.
The benefits of the design include simple and robust mechanical parts.
No gearbox, only a timing belt is needed between the motor and the
main shaft. The stepper motor is robust without any commutator or
brushes. Blocking the movement will not harm the motor. The table
may be turned by hand, even when powered, to obtain a suitable
reference angle. Due to the design, the torque will partly depend on
the actual angle for the motor. This modulation of the torque may
under certain circumstances create small vibrations that may be
enhanced by a resonance in the device placed on the table.
The torque of the device is limited in order not to harm the user or
devices placed on or around the turntable. Still it can carry
considerable loads in any direction. Note therefore that the loads have
to be balanced around the turning axis. If a large or heavy object is
placed on the table, increase the acceleration time in order to reduce
the torque needed for the acceleration.
The motor will try to keep the boom in the wanted position with a
torque similar to that from a spring force. The combination of this
force and the inertia of the moving mass will have a distinct resonance
frequency. Adjust the speed to keep away from this resonance which
otherwise may enhance the small vibrations from the motor.
User
interface
Indi-
cators
DSP
Power
amp
Power supply
Mains
Serial
interface
M
ot
o
r
Home
detector
Boom
axle
Summary of Contents for Nor265
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