#1 is the red wire, look at the picture closely.
Here is on the picture, the right way to connect the ribbon.
With for 50cm long ribbon, you can connect all the keys of a standard
keyboard, if you place the board in the middle, of course.
You can possibly, power an optical reader rank, under limit of 500 mA.
Please, adapt the power supply to this consumption. If it is over this limit,
please power the optical equipment directly with a different power supply, just
let the Gnd common to the 2 power supplies.
The inputs are “pulled down” by a 22ko resistor. Take this in account for your
photo-transistors.
L-H modes
The normal mode is H (high), ie the inputs are active (sending an note ON)
when we apply +5 volts.
Alternatively, in L mode, the inputs are active and sending the note ON when
the Gnd is applied to the input. This may be necessary, for example, with hall
effect detectors, to avoid over-consumption. You just need to change the
position jumper to choose your mode.
