geekhack
geekhack Projects => Making Stuff Together! => Topic started by: OldIsNew on Tue, 19 September 2017, 20:43:48
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After XMIT mentioned on another thread that he thought it was likely that the xwhatsit would work with KeyTronic foam and foil boards since they're capacitive like the Model F, I definitely wanted to try it and it works like a charm. I used the xwhatsit on a Westinghouse KeyTronic board with good results and this one is a TRS-80 Model II board. The case is somewhat flimsy plastic but I like the look and internally it's a "vintage" KeyTronic foam and foil.
[attach=1] [attach=2]
The old foam and foil had degraded as usual so I replaced it:
[attach=3] [attach=4]
Mapping the matrix is easy with these boards since they have such nice big conductive pads and it's just a matter of using a continuity tester to figure out which pads are connected to each other.
After that just recorded which IC pin corresponded to which row/column. Then desoldered the ICs and wired the xwhatsit to the pads.
[attach=5] [attach=6]
It's not even necessary to keep track of which PCB pads correspond to which keys since that all gets assigned in the xwhatsit Capsense Keyboard Utility.
[attach=10]
Interestingly the matrix on this board was 8 rows x 12 columns which was the same as the Westinghouse KeyTronic board. If it happens that KeyTronic stuck to the 8 rows by "x" column pattern then I would imagine almost any KeyTronic foam and foil could use the xwhatsit since the xwhatsit Model F can accommodate up to 8 rows by 16 columns. I have another KeyTronic PCB left over from another project and I'll probably trace that out to see if it fits the pattern.
I also sanded and repainted the case because it was a bit of a mess.
[attach=7] [attach=8] [attach=9]
This board is working well with the voltage threshold set at 193 (typing this with it) . I never got a TRS-80 back in the day because they were quite expensive and, as my father said, "Nobody needs a computer in their house!" At least I have a keyboard now.
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Wow this is awesome! I love mods like this. Maybe I'll add a controller to one of my old Keytronic boards.
I love all the guard traces they have on the PCB to prevent leakage.
Now I dont think these were all that great to type on: any thoughts?
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I love all the guard traces they have on the PCB to prevent leakage.
I do think it is a nice touch - someone put some thought into the board.
Now I dont think these were all that great to type on: any thoughts?
I like the switches actually. At least on the three older KeyTronic boards I have, I find the switches to be nice smooth linears. I really do like typing on them.
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OMFG! This is a bigger nostalgia trip than a K-TEL record! I remember the "Trash Eighty" from back in the day - never was in the financial league to buy one but I had rich friends who had them.
What a fantastic restoration/upgrade/modernisation project!
I remember having to repair an old foam and foil keyboard back in the eighties by gluing bits of aluminium foil onto pieces of foam cut to size - never had to do the whole board, though, just a couple of keys at a time. IIRC, I've got an old foam and foil board around here somewhere in my junk pile - doesn't date back to 1979, though.