User Guide

PAMS Technical Documentation System Module & UI
NHM-8NX
Issue 1 05/02 ãNokia Corporation Page 35
A new type of component is used for ringer melodies: a speaker.
The speaker is a 13 mm device from PSS. It's inherited from the 13mm earpiece (also
used by NHM-8) however with more height to provide opportunities for more displace-
ment for the speaker diaphragm. The speaker have a protective shield directly in front of
the diaphragm.
The speaker substitutes the original buzzer.
Alerting tones and MIDI melodies is generated by the speaker, which is controlled by a
sine driven output from UEM and an external amplifier.
The speaker implementation have two main resonances: 1.8 kHz and 2.9 kHz. The ringer
melodies is optimised for the given response so that the best possible (and loudest possi-
ble) tones will be implemented.
Acoustical wise the back of the speaker is designed to be completely tight, with a well-
defined volume. The volume is kept under control by a semi-adhesive gasket mounted on
the back of the speaker, and the PWB.
A double-adhesive gasket is being used on the front of the speaker to provide sealed
conditions from front to back. In front of the speaker there is a well-defined volume
which connects into the sound-port holes in the D-cover.
The speaker is electrically connected to the PWB by spring contacts (similar to that for
the internal earpiece).
Figure 10: Interface between the MIDI-circuit and the UEM
Accessories
Batteries
100k
HFCM
HF
XEARP
XEARN
UEM
INT
10n 10n
10
10
HEADINT
10n
47k
100k
IN-
SALT
Vo1
Vo2
42 ohm / 100 MHz
42 ohm / 100 MHz
UPP
GENIO14
IN+
BYPASS
1u
SHUTDOWN
External audio interface
Interface to
DC-out
Vdd
1u
GND
Vbat
100k
47k
10n
27p
10n 10n
1u
Placed near
UEM
Placed outside
BB-can, near
SALT