hi,
again back to how to realize preset keys with rubber boards ( length of 12 keys )
When You have the sheet of printed rubbercontact board You have to "unplug" some rubbercontacts
to see how they are made , specially the routing
Rubber contacts principially are made of a pair of "routed fingers" and the contact area is plated golden.
The rubbercontacts itself are of dynamic kind so with the key You close thes pair of contacts one after another.
The first rubbercontacts are connected at one end together. You have to find out which of the two is realized
in this way. The second "finger" will run to one plugpin of the matrix.
The matrix itself is for preset contacts
never needed so You have than to separate this.
The result so must be
one common contact connected to GND
12 separate contacts for the wanted 12 preset keys.
So sometimes ( case of used sheet of rubbercontact board ) it is necessary to cut layout lines and to connect
some layout lines.
The whole wiring must be done with the
thinnest wire You can find.
Best way is the use of some thin isoltated
coil wires. The reason of thin wires is the fact that You
sometimes must go under the rubber itself to realize the needed connections
Because the second finger rubbercontact is connected same way for the second dynamic contact it is a good idea
to connect the two rubber contacts of each key in PARALLEL. It´s not needed but better ..........
If only one contact in use chose the first one being closed by key
In final result You must have than a terminal with 13 connectors :
TWO for GND and the 12 needed keys ... ie use a 14 pole flatcable plug mounted directly under the rubber board.
For connection to preset 12- 2 board than use a little "Adapter board selfmade " to needed board connection