TONE PRODUCING PRINCIPLE
The Model 112 Wurlitzer Electronic Piano utilizes as a tone
generator a free reed (No. 17, Figs.
5
and
6)
actuated by a
piano hammer (No.
16,
Fig.
6)
and damped by a damper
(No.
26,
Fig. 6) with an action similar to a standard piano.
The musical range of the instrument is 64 notes beginning at
"A"
55
CES·
On a conventional piano this would be keys Hl3
through
H76.
The tone pick-ups (No.
25,
Figs.
5
and
6)
are
insulated (No.
18,
Figs.
5
and
6)
from the main bar
(No.15,
Figs.
5
and
6)
and are mounted so that the reeds vibrate
through the opening when struck by the hammer. These tone
pick-ups are the fixed plates of a condenser in the capacity
change system. The reeds should be adjusted so that the free
swinging reed clears the pick-ups but NEVER contact them.
The pick-ups have a polarizing voltage of 140V through a
470,000 ohm resistor and are not a shock hazard. As the reeds
swing away -(down) from the pick-ups, the capacity decreases.
The capacity change takes place in accordance with the tuned
pitch of the reed. This change produces a varying voltage
across a load resistor. The voltage is then amplified through
the console amplifier.
LEAD WEl�HT
Fig. 5
-7-
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