National Instruments Signal Processing Engineering Educational Device NI SPEEDY-33 - Manual (Page 18)

Chapter 2 NI SPEEDY-33 Functional Description and Interface
NI SPEEDY-33 User Manual 2-6 ni.com
Power Port
Caution Do not connect the power source to the power port while the NI SPEEDY-33
device is connected to the PC.
The power port (J10) can supply the NI SPEEDY-33 with external power
when operating the device in standalone mode, without being connected to
the PC through USB. When power is supplied to the device, the power LED
lights.
The input voltage must be 9 VDC, at 500 mA, with the outside contact
being ground and inner contact being positive VDC. An appropriate
2.5 mm jack can be used in conjunction with a 9 V battery (pack) to
optionally supply power for battery-powered applications. Refer to
Appendix A,
Specifications , for complete power supply specifications.
Audio Stereo Input Port
Audio input can be connected to the audio stereo input port (U11).
Caution Ensure that line level audio signals are not connected to the audio input when the
NI SPEEDY-33 is configured for microphone level. It is possible to damage the audio input
circuitry by overdriving the input.
If an external microphone is used, it should be capable of operating with a
standard stereo jack; not all microphones will work in this fashion. Many
PC microphones will not work because they require a DC voltage to be
driven on one of the inputs. Traditional mono microphones generally work
fine.
It is important to ensure that the audio input level jumpers (J1, J2) setting
is configured appropriately for microphone level or line level, depending
upon the audio source connected to this port. Refer to the
Audio Input Level
Jumpers section for more information.
Note The onboard microphones are disconnected by mechanical disconnect when an
audio source is connected to the audio stereo input port.
Audio Stereo Output Port
The audio stereo output port (U14) can be connected to a set of stereo
amplified speakers. Typical amplified speakers used for PC sound should
provide good output. You also can plug external headsets to this port,
although there is no hardware control over the output gain or signal level.