Microsoft LPF-00004 Manual del operador descargar pdf (Pagina 39)

GENERAL INFORMATION Page 21

CYBERAMP 380, COPYRIGHT MARCH 2002, AXON INSTRUMENTS, INC.

8) Experiment. While hum can be explained in theory (e.g. direct pickup or ground loops), the

practical reduction of hum is an empirical matter. Following the rules above is the best start.

The final hum level can often be kept to less than 1 µV

p-p

, input referred. One technique that

should

not

be used to reduce hum is the delicate placement of cables so that a number of

competing hum sources cancel out. Such a set up is too prone to accidental alteration.

Power-Supply Glitches

The CyberAmp 380 has been designed to minimize the effects of AC line voltage transients (glitches).

Some AC line voltage glitches may, however, cause transients to appear on the outputs and this may

corrupt sensitive recordings.

Immunity from AC line voltage glitches is only gained by eliminating them at the source. Most

glitches are due to the switching on and off of other equipment and lights on the same AC circuit.

Precautions to be taken include:

1) While recordings are being made, avoid switching equipment and lights on or off.

2) Water baths, heaters, coolers, etc. should operate from zero-crossing solid-state relays.

3) Radio frequency interference (RFI) filters should be installed in glitch-producing equipment.

In most cases an occasional transient on the outputs is inconsequential and no precautions need be

taken.

Safety

The CyberAmp 380 and associated probes are not intended to be used and should not be used in

human experimentation. Nor should they be applied to humans in any way UNLESS specially

identified, isolated probes are used. Such probes are clearly identified by one of the symbols

shown in Figure 1.

It is unsafe to connect human subjects directly to the CyberAmp, or to any probes that are not

marked with one of the symbols in Figure 1.

Input Coupling

The proper coupling to a CyberAmp 380 input depends on the type of probe that is used.

Each AI 400 series SmartProbe has a recommended coupling, such as single ended or differential, AC

or DC. This information is found in the instruction sheet for the probe, and is also contained in the

SmartProbe's memory chip, and so is available to the host computer.

If the input is via the BNC input, the negative input coupling must be set to GND. The positive input

coupling may be set to DC or AC, depending on the signal.

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Microsoft LPF-00004 Manual del operador Pagina 39