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Finally - a keypad for the Elf 2000!

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  • Robert Armstrong
    Some time ago I promised to build a hexadecimal keypad for the Elf 2000, but I was never able to find push buttons that I was happy with. Well, I was
    Message 1 of 1 , Jan 26, 2006
      Some time ago I promised to build a hexadecimal keypad for the Elf 2000,
      but
      I was never able to find push buttons that I was happy with. Well, I was
      wandering the aisles of a local surplus store (this is Silicon Valley!) and
      found a box full of beautiful push button switches. I bought the whole
      box - that's all the store had - and designed a keypad around the buttons.
      They weren't cheap, but they're worth it.

      The buttons are perfect. They remind me a little of old style touch tone
      telephone buttons, but these are individual buttons rather than a single
      4x3 keypad. They're a little large, but have a wonderful feel. Better yet,
      they have a slot in the top so slip a small piece of paper with a legend
      under the keycap. And best of all, some have a hole in the bottom that will
      accept a T1 LED or grain of wheat bulb so that they can be illuminated. As
      the Big Z said, "Amazingly amazing!"

      Here's a photo of the prototype keypad -

      http://www.sparetimegizmos.com/Hardware/images/keypad-small.jpg

      There are 20 buttons total - 0-F hexadecimal, RESET, GO (run), LOAD, MEMORY
      PROTECT and INPUT. It doesn't show up well in the photo, but there are
      actually small legends on the five function keys underneath the big letter.
      I'm thinking about putting the binary code (e.g. "1010" for A) underneath
      each of the hexadecimal keys too. The legends are printed on regular paper
      with an ordinary printer, so they're easy to change.

      The five function buttons are back lit with LEDs. RESET, GO, LOAD and
      MEMORY PROTECT all light up when the associated condition is true. The
      INPUT
      button lights when any numeric key is pressed and then goes out when INPUT
      is pressed.

      Finally, there's a small beeper (the black disk in the lower right corner)
      and all twenty keys generate a short key beep when pressed. A little over
      the top for an Elf keypad, I admit, but it looks and feels nice.

      I have enough of the buttons to make six keypads and I intend to order six
      PC boards. Since the PC boards and buttons are inseparable, I'll be selling
      them together as a kit of one PC board and twenty buttons for $75. That's
      a little more expensive than I wanted, but an order of only six PC boards
      is not very economical.

      BTW, the PC board in the photo is a prototype. You can see a few jumper
      wires on it, and it's not silk screened or solder masked. The "production"
      boards will of course be solder masked (so they'll be the same dark green
      color as the Elf PC board) and they'll be silk screened with the usual
      stuff.

      Let me know if you want one, and I'll take your order.

      Thanks,
      Bob Armstrong
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