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@@ -84,9 +84,9 @@ Note that for a cost analysis you often have to give the dimensions of the PCB,
For a keyboard with real buttons.
on September 8, 2022. I finished my keyboard PCB, revision 1.1. I uploaded the schematic, the PCB production files, a Bill of material specifically for the keyboard, and a keyboard overlay (.PDF) which you can print out, laminate with transparent plastic, punch holes for the 40 keyboard plungers, and glued on top of the buttons.
and a Bill of material for the keyboard with 40 keys a power LED, and solder pads for three flatcables, that are prepared so that they have wire ends with 2.54 pitch (every other wire with an 1.27mm pitch is not used) three flexcables are used with 5-wires 3-wires (for the LED) and 8-wires).
revision 1.2 was made because there were some errors in the lettering below the keys, now the text "T Y U I O P" is corrected and the "10" was changed to "0", also the lettering was made a bit bolder. This change only pertains to the silk screen, nothing else has changed. so you can use the revision 1.1 BOM and KiCad files (you will need to edit the lettering though). If you already made a revision 1.1 PCB, no worries, the lettering is not needed when you use the keyboard overlay, and nothing else has changed. The copper text on the keyboard still reads 1.1. as copper was unchanged, only the silk screen was modified.
revision 1.2 was made because there were some errors in the lettering below the keys, now the text "T Y U I O P" is corrected and the "10" was changed to "0", also the lettering was made a bit bolder. This change only pertains to the silk screen, nothing else has changed. so you can use the revision 1.1 BOM and KiCad files (you will need to edit the lettering though). If you already made a revision 1.1 PCB, no worries, the lettering is not needed when you use the keyboard overlay, and nothing else has changed. The copper text on the keyboard still reads 1.1. as copper was unchanged, only the silk screen was modified. Nothat when ordering the PCB you often have to give PCB dimensions for cost assesment, for the keyboard the dimensions (as said above) are 158mm wide and 64mm high.
# optional cassette replacement device
I have also designed a very simple variant of the TZXDuino, an Arduino nano based playback device that can convert a .TZX file for a sinclair spectrum, or ZX-81 from a SD-Card to an audio signal that can be used to load a cassette file (game) into a sinclair computer, you can find it as the TZXDuino Pico project on the mahjongg2 github pages. I plan to use it to test the cassete interface of my ZX81+38 clone.
I have also designed a very simple variant of the TZXDuino, an Arduino nano based playback device that can convert a .TZX file for a sinclair spectrum, or ZX-81 from a SD-Card to an audio signal that can be used to load a cassette file (game) into a sinclair computer, you can find it as the TZXDuino Pico project on the mahjongg2 github pages. I plan to use it to test the cassete interface of my ZX81+38 clone. The PCB is very small only 37.1 mm wide, and 47.2 mm high and it is a 2 layer board.