Are there any kits out there for what I want to do?

Discussion in 'General Electronics Chat' started by Cory Duchesne, Mar 25, 2010.

  1. Cory Duchesne

    Thread Starter New Member

    Mar 25, 2010
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    Hello,

    I've been trying to understand CPU's/microprocessors lately, and I realized today that I want to explore building circuits with breadboards. But what I want is to somehow setup a very, very simple keypad to the breadboard, with keys 0 to 9, like you see on a calculator. And then I want a 7 segment led display, so that whatever number I press, shows up on the display. And of course I would have to build whatever circuits are required to display one of the 10 numbers I have in mind.

    I don't want to do anything beyond displaying numbers. No arithmetic, I don't want to make a clock, nothing like that.

    Just a keypad, and the ability to use that keypad to display numbers 0 to 9.

    I've typed into google every possible keyword I could think of in search of hobby kits for this kind of thing, but all I come up with are projects that are much more complicated than I want to do.

    So....can any of you help me with this? Any advice?
     
  2. Wendy

    Moderator

    Mar 24, 2008
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    That is simple enough, but I don't know of any kits for it, though they may exist. A CPU style circuit will use hexadecimal though, 0-9, and A-F.

    There are several decoder chips for what you're wanting to do, something like the CD4511 or the 7447. 4 flip flops to capture the number feeding the decoder. The circuit is actually pretty simple overall.
     
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  3. Wendy

    Moderator

    Mar 24, 2008
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    PackratKing and Cory Duchesne like this.
  4. studiot

    AAC Fanatic!

    Nov 9, 2007
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    These things used to be readily available

    I thought perhaps your requirements would be a bit out of date and in fact I found an 8x8 LED matrix kit on the first page of googling
    "experimental breadboard kit"

    However the following came up on page 2

    http://suppliers.jimtrade.com/109/108317/135339.htm

    So they are still about. You can sometime find cheap ones on Ebay.
     
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  5. Cory Duchesne

    Thread Starter New Member

    Mar 25, 2010
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    yeah, thanks, that seems to strike close to what I'm looking for. But I'm a bit dissappointed that it uses a chip (the 4511 decoder/driver). Isn't the whole point of a breadboard to simulate what happens in chips? I don't like chips because I can't make them myself, I can't tinker with them to see how they work. I was hoping with a breadboard, I could engineer/simulate one of the most primitive and simple chips possible. Just a keypad feeding numbers to a simple display.
     
  6. SgtWookie

    Expert

    Jul 17, 2007
    22,182
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    Buy one of these:
    http://www.radioshack.com/product/index.jsp?productId=3814337
    The Electronics Learning Lab was designed and the manuals written by Forrest M. Mims III, a noteworthy citizen scientist. The manuals are not error-free, but they are pretty good.

    You will find the lab useful well beyond what's in the manuals.
    The 2nd manual is available online:
    http://www.radioshack.com/graphics/uc/rsk/Support/ProductManuals/2800027_P2_PM_EN.pdf

    As far as driving a 7-segment display from a keypad-type layout of switches, that's not too hard to do using basic normally-open switches and diodes (like 1N4148/1N914) to select which segments to light up depending on which button is pressed.

    You will need to use current limiting resistors for each of the seven segments.
     
    Last edited: Mar 25, 2010
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  7. Cory Duchesne

    Thread Starter New Member

    Mar 25, 2010
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    Thanks. It looks a little too complicated. Can't I just have a plain, bare bones breadboard and engineer some circuits so they display numbers to a 7-seg LED?
     
  8. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    As far as driving a 7-segment display from a keypad-type layout of switches, that's not too hard to do using basic normally-open switches and diodes (like 1N4148/1N914) to select which segments to light up depending on which button is pressed.

    You will need to use current limiting resistors for each of the seven segments.[/QUOTE]

    Design-simple, exicution a little messey. Keypads available with a common & individual sw leads[ All Electronics # KP-12 ]or matrix, 3X3, 3X4, 4X4. Thumbnail is bare bones, if switches are rated at better than 100 mA ,can be used as shown[ 500 ohm & red LEDs @ 15 mA], but with keypad rated @ 20mA /key a transistor driver for ea key is required. Can be implemented with several plug strips. Let questions fly!!
     
  9. davebee

    Well-Known Member

    Oct 22, 2008
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    What you need is a digital logic breadboard, a power supply, some basic logic ICs, some wire and a book or two of starter projects. You'll also probably need a few parts like individual LEDs, resistors and capacitors.

    There are plenty of boards that add all kinds of accessories that raise the price and make them seem complicated, so it would be up to you to select the board that offers the one that you want.

    To specifically get a 10 button keypad and a seven segment LED, you may well need to buy them separately and add them to a simple board.

    If you are a beginner to digital logic, then even that circuit you suggest is fairly advanced. You might be better off starting with a single pushbutton and a single LED, and learn about gates and latches and counters; getting experience building working circuits with just those few parts would be a great way to get started.
     
  10. loqwan

    New Member

    Dec 15, 2009
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    Here is a keypad from parallax...I built and ran a boe-bot kit from them; very educational for a total beginner like me.
    http://www.parallax.com/StoreSearch...List/0/SortField/4/ProductID/194/Default.aspx
    Also they have kits for different things but instead of having to buy "their" kits, they have the texts for projects in free pdf's and the generic electronic parts lists so you can browse projects and see what you might like. Also provided a link for Arduino projects and parts, good basic projects to get started.
    Good luck to you,

    Loq

    http://www.makershed.com/SearchResults.asp?Cat=43
     
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