OpenEEG
Case Cabling

Open EEG Case and Cabling

This document assumes that you have pre-assembled PCBs, and documents how they are placed in a case.

Required Parts

The case covering the analog boards should be made from a ferrous (magnetic material) because the biggest source of interference is the 50/60 Hz power line hum which is a form of magnetically induced interference. Aluminum cases are useless for shielding this type of interference. The cables could be and any metal shielded coaxial cable.

The following parts can all be obtained from an electronics store (except the warning)

A print copy of the OpenEEG WARNING Document .
Small metal case with internal dimensions of 100mm x 80mm x 20mm (this will contain the analogue PCB)
Large plastic case with internal dimensions of 130mm x 100mm x 120mm (the 130mm x 100mm needs to allow for the externals of the small metal case, and the 120mm allows for the small metal case + the mounting of 3 digital boards, in case you want to expand to that size someday, although these directions do not cover it). The case will probably need to be a little bigger to accomodate the internal side of the sockets, and the battery
A 9-pin serial cable (typically female on the end that plugs into the PC, male on the other end)
9-pin d-sub Serial socket (female, to plug into the above cable) and some wire (to connect it to the digital board)
34-pin IDC cable (PCB-to-PCB cable) (Someone said that this can be made by cutting a floppy drive cable down to size)
9V battery (not powerpack) and 9V battery clip
Some wire to cable up the electrodes (including DRL). I’m unsure what’s best here (certainly shielded), but I’ll try to find out [TODO]
3 [TODO: Type] sockets (to be mounted on the outside of the case for the electrodes)
Pinhead female sockets (see FAQ for details about pinheads, but note that you need sockets, whereas “plugs” are pictured in the FAQ):

Pins	Pieces
2	3
3	3

Preparing the Parts

Case

Metal case

Fit the cases with: [TODO: find out how the links go out through the metal case]

Plastic case

Fit the case with:

The 9-pin, d-sub Serial socket
The [TODO: Type] sockets for the electrodes and the DRL
Mounting points for the PCBs

Cabling

Hook the 9-pin Serial socket into the 3-pin Pinhead connector (using some wire). Hook the pins in the order RXD, TXD, GND1, so that the Serial pins of those names can be connected to the digital board pins of those names
Hook the 9V battery clip into a 2-pin pinhead socket
Hook the remaining two 3-pin pinheads to the [TODO: Type] sockets (for electrodes)
Hook one 2-pin pinhead to the remaining [TODO: Type] socket (for the DRL)
You have a 2-pin pinhead left for the Calibration hookup [TODO]

Joerg Hansmann posted some good instructions for assembling IDC ribbon cables. I
copied-and-pasted those instructions to the electronics wiki