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just above the beginning of a 7 "plate Because the distance of the P.U. is more than 25 cm (10") plates
and the times used are almost the same, the speed must be different for both cases. If you set the
number of revolutions of the turntable to 33 1/3, then this difference can be observed very clearly.
7. H orizontal movement of the pick-up arm for the 17.5 cm discs
As we already know, it is necessary to pass discs having a diameter of 7"/ 17.5 cm, that the diameter
device is brought to the position of 17, 5 cm. For this the
Let us stand at the moment when the pick-up arm is brought from the inside to the outside. This
happens in the normal way already described. The
and then encounters the
the end of this hook touches a pin on the large guide hook
guiding hook and thus also the PU arm is moved even more inwards. This difference in spinning is
determined by the distance (X Fig. 9). With respect to the
from the inside to the outside and abandons it at a certain moment. Under the influence or torsion
spring (117), this hook goes back and
longer moved, and the pickup arm is just above the edge of a 17.5 cm drive. As the path traveled by
the pick-up arm is larger than for 25 cm discs, and the times spent on it are substantially the same, the
speed must be different in both cases. When setting the speed of the platter to 33 1/3, this difference
in speed is very easy to observe.
P9a
8. P utting the c ontrol disk into motion at the end to a disk
In order to achieve this, the drive device/carrier is moved to the main shaft on the control disc just
like when it was s tarted . However, this is not happening under the influence of the s tarter spring 27 FIG
9. , but in a different way . The driver (
just friction will, as the P.U.ARM is moved inwards through the grooves of the gramophone record,
touching the catch /DRIVER
turn completely free around its bearing point and the nose will slowly be turned in the direction of the
main shaft. As long as the needle does not yet run into the outlet groove, the nose must not be touched
by the cam ( D fig. 8 ) on the shaft, otherwise the plate would be terminated too soon. To prevent this,
the
f iber disc (128 FIG 9
shaft at the end of the plate, the nose will not be hit. After the P.U. Once a groove has been turned
inwards, the disc will g et a tap of the cam on the shaft again and the driver on the
pushed back a bit. This continues until the needle enters the outlet groove and causes a large, inwardly
directed
cceleration o f the
a
movement, the carrier on the
fast
be hit by the ridge and the
outlet groove does not start at the same distance from the middle of all plates and thus serves to
accommodate these differences. T he accurate setting of the
switching on of the mechanism . At the end of the disruption of the
s mall guide hook
112
. It turns around its axis. The spring (113) attached to
b
ut
against the diameter device. now the
1 20 FIG 9.
( 127 FIG 9
) on the control disc towards the end of the plate. The latter can
) should be used. Because this disc is pushed back and forth by the cam on the
s teering hook
and thus also the attached driver ( 1 20 FIG 9 ) . Because of this
C ONTROL DISC
C ONTROL DISC
i n motion. The
s mall guide hook
c ontrol
disk
continues to rotate at a constant speed
(
B
fig9
) so that it also turns to turn. By the
s mall guide
)
fastened to the
F RICTIONALLY
is now also moved
q uickly
f iber
disc is actually only present, because the
f
riction
i s important for the timely
C ONTROL DISC
(112)
comes into operation.
hook
112, the roller rotates
l arge guide
hook
s teering hook
s teering hook
, so that the nose can now
, the catch is pushed
is no
1 11 FIG 9 ,
will be
21
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