**STEP n°4:** assemble Ohmpi 
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   +--------+------------------------------------------------------------+
   |        |   .. image:: step_n_4/step_4_1.jpg                         |
   |      1 +------------------------------------------------------------+
   |        |Cut 4 ribbon cables composed of 16 wires each to the proper | 
   |        |length (about 1.5m). Each wire corresponds to an electrode. |                                                                      
   +--------+------------------------------------------------------------+

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   +--------+------------------------------------------------------------+
   |        |   .. image:: step_n_4/step_4_2.jpg                         |
   |      2 +------------------------------------------------------------+
   |        |Crimp the ribbon cable on the corresponding idc connector   | 
   |        |with a suitable clamp. Pay attention to the direction of the|                                                                      
   |        |cables. Unbalanced IDC connector. The ribbon cable must be  | 
   |        |perpendicular to the connector.                             |
   +--------+------------------------------------------------------------+
   
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   +--------+------------------------------------------------------------+
   |        |   .. image:: step_n_4/step_4_3.jpg                         |
   |      3 +------------------------------------------------------------+
   |        |Example of IDC connector mounting. The wires should run as  | 
   |        |perpendicular as possible to the IDC connector.             |                                                                      
   +--------+------------------------------------------------------------+   
   

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   +--------+------------------------------------------------------------+
   |        |   .. image:: step_n_4/step_4_4.jpg                         |
   |      4 +------------------------------------------------------------+
   |        |Same for a 6 wires ribbon cable of 1 m length.              | 
   |        |                                                            |                                                                      
   +--------+------------------------------------------------------------+  

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   +--------+------------------------------------------------------------+
   |        |   .. image:: step_n_4/step_4_5.jpg                         |
   |      5 +------------------------------------------------------------+
   |        |Cut the ribbon cable flush with the IDC connector.          | 
   |        |                                                            |                                                                      
   +--------+------------------------------------------------------------+  

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   +--------+------------------------------------------------------------+
   |        |   .. image:: step_n_4/step_4_6.jpg                         |
   |      6 +------------------------------------------------------------+
   |        |Position 9 spacers above the MUX board, and 9 spacers below.| 
   |        |                                                            |                                                                      
   +        +------------------------------------------------------------+
   |        |   .. image:: step_n_4/step_4_7.jpg                         |
   |        +------------------------------------------------------------+
   |        |Profile view for mounting the spacers above and below.      | 
   |        |                                                            |                                                                      
   +--------+------------------------------------------------------------+ 

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   +--------+------------------------------------------------------------+
   |        |   .. image:: step_n_4/step_4_8.jpg                         |
   |      7 +------------------------------------------------------------+
   |        |Cut a 50 cm long wire of any color (here yellow). Strip and | 
   |        |tin each end of the wire. Install the wire "A" on the screw |
   |        |terminal of MUX board « A ».                                |                                                                                       
   +--------+------------------------------------------------------------+


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   +--------+------------------------------------------------------------+
   |        |   .. image:: step_n_4/step_4_9.jpg                         |
   |      8 +------------------------------------------------------------+
   |        |Cut a red wire and a black wire of 50 cm length. Strip, tin | 
   |        |and position the wires on the left screw terminal as shown  |
   |        |in the picture: i)Red wire 12 V, ii) Black wire GND         |                                                                                       
   +--------+------------------------------------------------------------+
   


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   +--------+------------------------------------------------------------+
   |        |   .. image:: step_n_4/step_4_10.jpg                        |
   |      9 +------------------------------------------------------------+
   |        |Mount the 4 ribbon cables (16-wires each) with IDC          | 
   |        |connectors. A small noise is often heard when the IDC       |
   |        |connector is clipped in place.                              |                                                                                       
   +--------+------------------------------------------------------------+