Optical Isolation Box

 

The Isolation box, takes triggers from a DB25 source and creates an optically isolated and a non-optically isolated BNC trigger. Power comes from a battery pack through DIN6 power cords. The trigger source will typically be a DB25 cable coming from a laptop running Presentation software.

The BNC cable attached to the optically isolated output is connected a BNC>>2 female eeg plug adapter. The reference is jumpered to one of the EKG leads and the isolated trigger is

Jackbox from a bedside monitoring station (This particular picture is from an EEG subject, but the same jackboxes are used. Typically in iEEG, many jackboxes are used with reference and ground jumpered from one jackbox to another). For intercranial grid subjects, the ground and reference are attached to the skull during surgery. During testing, the ground must never be removed from the patient: potential shock risk and noise source. The reference can be temporarily removed if it is necessary to do so, but remember to replace when done. It is advised to have an EEG tech check that the clinical recording system is ok after we are done with testing.

 

Iso 124 Chip Specs: http://focus.ti.com/lit/ds/sbos074c/sbos074c.pdf

 

Testing Procedure

Setup:

  1. Connect the BNC optically isolated output of the isolation box to the Protek Scope using the BNC red/black wire splitter.
  2. Connect the computer to the parallel input port of the isolation box.
  3. Connect the power supply to the isolation box.
  4. Open Presentation–>Settings Tab–>Port Button–>Select 1 in Output Ports section–>Test Output Ports

 

 

Testing:

  1. Flip the switch to Hi.
  2. Enter 255 for Code and 2500 for Pulse Length. Press Send.
  3. A square wave should appear on the scope with a voltage of
  4. Flip the switch to Lo and send another pulse. The square wave should have a voltage of
  5. Repeat steps 1-4 for the BNC non-isolated output of the isolation box. Test for the following pulse voltages:

___V for Hi and ___V for Lo.

Testing Resistance:

  1. Disconnect the power supply.
  2. Using an ohmmeter with a wire connected to the positive test probes.