NEDSP900 Development Board
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5.2
Headphone/ Speaker output
This is provided using a TDA2822 low power amplifier. This is ideal for headset listening and small
speakers only. It can drive into loads as low as 4 Ohms. The Audio level is set by RV65 a & b, located
adjacent to SK10 which is the output socket.
6.0
Other facilities on the Board
To allow for monitoring of both input and output audio signals as well as allowing for external control of
the NEDSP900 module from signals ‘off the PCB’ provision has been made for additional connectors,
some of them already fitted and their use is easily identifiable from the Circuit Diagrams (see Appendix
A).
6.1
Audio Monitor Points
A set of audio Monitor points has been provided for the user to ‘hook’ into the audio
signals before and after the DSP module allowing for monitoring, signal injection and
signal extraction from the Module.
These connections all use Molex KK connector series (see Connector Specifications –
section 7.0). Their Pin outs are as follows:
Pin 1 = Channel 1, Pin 2 = Ground, Pin 3 = Channel 2
PL18
is the NEDSP900 Input Audio Monitor. Do not load these pins with impedances of
less than 100kOhm
PL6
is the NEDSP900 Output Audio Monitor. Do not load these pins with impedances of
less than 100kOhm
PL7
is the NEDSP900 Buffered Audio Monitor. Do not load these pins with impedances
of less than 10kOhm
