BRUEL & KJAER 2305 - Electromechanical System Components

Two-Channel Selector. This selector is operated by means of interchangeable
cam discs mounted on the Drive Shaft II and can be used for a number of
purposes, such as time marking, two-channel intermittent recordings, control
of external switching systems, automatic recording of reverberation curves,
etc.
The Two-Channel Selector can be moved out of function by means of
a
cam arrangement whioh can be screwdriver-operated through the right-hand
cover plate, see Fig. 2.3.
Electromechanical System.
The electromechanical circuit consists of the drive motor, the electromagnetir
clutch and the event-marking and pen-lifting arrangements.
Synchronons Motor. The motor is of the single-phase synchronous type. The
rotating electromagnetic field is produced by connecting a capacitor in series
with
one of the three motor windings and connecting this series L-C circuit
parallel
to one of the two remaining windings. Dependent upon which one
of the windings is paralleled by the series circuit, the motor will rotate in
one
or the other direction . The direction of rotation is controlled by means
of the switch marked FORWARD-REVERSE on the Recorder top panel, see
also Fig. 1.9.
o ,: ~----,
Forward : Reverse
I
Power Supply
Event
Marking
Event
Marker
Switch for 2112
Control Pulses
/'
~DriV. Shaft I
Lifting
Magnet
.)To be used with Com-
bined Units
Type 3313 and 3326
Two-Chomel
Selector
160~.5f
Fig. 1.9. Basic diagram of the electromechanical circuit.
Electromagnetic Clutch. To allow immediate transfer of drive power at
correct speed of rotation when the recording is started, the motor can be
kept
running and the recording commenced by connecting the motor to the
gear-box
with the aid of an electromagnetic non-slip clutch. A switch marked
16