Multi-Functional Electrode Headbox (MFHB)

click photo for larger image

DESIGNED SPECIFICALLY FOR INVESTIGATIVE RESEARCH, THESE HEADBOXES OFFER THE FOLLOWING FEATURES WHEN USED WITH SAI ISOLATED BIOAMPLIFIERS:

Accepts loose-lead electrodes and/or ELECTRODE-CAP inputs. Each channel has a set of front-panel differential-input jacks which are also parallel connected to an input "D-sub" connector which is the input for the E-CAP and for the calibrator test-signal cable.
Front panel jacks facilitates the patching of specific loose-lead electrodes into desired channels and also permits the differential amplification of two electrodes in lieu of referencing against the "REF" electrode.
Each input has a three-position mini-toggle switch: "REF", "OPEN", and "GND" positions; these are configured in horizontal rows of 12-channel sets, vertically expandable to any number of channels. These switches are used as described below and also to perform electrode impedance tests when the headbox includes this optional impedance measurement system.
1. In the "REF" mode the (-) input of the channel is tied to a common reference buss which is in turn connected to the signal source reference point via the front panel "REF" jack or from an E-CAP electrode. The (+) input can then be connected externally to a loose-lead electrode or internally to an E-CAP electrode via the "D-sub" E-CAP input connector. This "REF" mode simplifies the connection for the classic "monopolar"configuration.
2. In the "OPEN" mode both inputs of the channel are available to accommodate a loose-lead electrode pair direct or from an E-CAP pair (via the "D-sub" input connector); this constitutes a "bipolar" connection into the BIOAMP.
3. In the "GND" mode both inputs of the channel are connected to the BIOAMP isolated common (ISO GND); this to prevent glitching of other active channels by unused/open channels.
A headbox Z-METER option enables the measurement of loose-lead and E-CAP electrode impedance using a built-in digital readout system . The range is 100-199k Ohms using a 10 mA / 30 Hz test current.
Headboxes are designed to minimize electrical noise pickup by using symmetrical strip-cabling with adjacent-wire pairing for each channel. These pairs make the connection into the BIOAMP'S very-high 50/60 Hz common-mode rejection, true-differential preamps. Various cabling options are available to conform to special requirements.
Calibration test-signal source jacks are also available on the headbox. Testing is enabled by connecting a calibration cable between a Cal-Source jack and the "D sub" E-CAP / CALIBRATOR input; this simultaneously connects the cal test-signal into all channels of the BIOAMP and all outputs can be analyzed.
This configuration tests the complete BIOAMP system from end to end, in effect replacing the E-CAP as the signal source; this helps to quickly determine if a problem is internal or external to the BIOAMP. Cal test-signal source jacks are also available on the BIOAMP to test the system without the headbox.