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Discussion in 'Electronic Design' started by amiller, Dec 22, 2005.

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  1. amiller

    amiller Guest

    I have started adapting my daughters toys for external switches so she
    is able to operate them. She has Spinal Muscular Atrophy which limits
    her movement to hands and feet. So far it has been very simple,
    soldering wire to whatever existing switch is in her toy and running
    the wire out to a 1/8 plug.

    She has several toys that operate on multiple internal switches and
    each switch does something different. For example a doll that says
    something different when you touch the left hand verses the right hand.
    What do I need to do create one switch that cycles through all the
    abilities or switches of a single toy. I can imagine a setup that with
    each click of her switch the toy cyles through all the actions: left
    hand, right hand, left foot, right foot. Also if you guys have any
    advice on learning more design in general I would appreciate it.
  2. Tim Wescott

    Tim Wescott Guest

    You could do this with a CD4017 CMOS Johnson counter and a bunch of
    relays. If I were 20 years older I'd probably know how to do it with
    just relays, but I'm not...
  3. Bob Stephens

    Bob Stephens Guest

    Sounds like a worthy project, and I'll be happy to help if I can. Would she
    be able to operate a small keypad with buttons on it? Something like the 4
    arrows for channel and volume on a TV remote comes to mind.

  4. Tim Wescott

    Tim Wescott Guest

    I should have thought of that. Oh well, I must be senile. Too bad I'm
    only in my 40's.

    If she has real motor control problems it may be better to get something
    with really huge buttons -- there's a game out that's sort of a "follow
    the leader" game, called "Simon" I think, that has four really huge
    buttons. At any rate, a cruise through Toys-R-Us should yield something

    You could come off of each one of those to a separate pair of wires,
    then use a big ol' DB-9 (serial) connector to plug into them.
  5. yep, a good project.
    just been surfing, and was looking at non USENETstuff like

    That's an "audio " forum.It's a typical but very focused forum
    There are probably similar focused forums that might be suitable for
    the OP.
    But I don't know how I would find them, google is such a pain in the
    arse these days.

    Just searching for a data sheet never takes you to the source of the
    datasheet on the first page anymore, just internet xerox machines

    Oh, for a directory of the internet :-(, without popups. Or just
    yellow pages, in black and white!

  6. Ted Edwards

    Ted Edwards Guest

    You don't say anything about age or mental ability. If you think she
    could handle learning a bit (sic) of binary, a keypad with four
    press-to-make switches for four fingers and one to hit with the thumb
    for setting the choice could give her fifteen choices (not using zero)
    from one hand. It's the sort of thing that might take a day or two to
    get used to but would then be automatic to her.

  7. Thomas Magma

    Thomas Magma Guest

    Perhaps a panel mount rotary switch . Then a decent sized knob turning to
    each position and playing each audible sound. You might even be able to get
    several different toys on one switch, then paint the different pictures of
    each toy on the panel around the switch. Do the sounds repeat themselves if
    you leave the switches closed? because that might not be the best unless you
    leave one rotary position open for the 'off position.

    I'm guessing that each switch has a weak pull-up wire and a common ground
    wire going to it. So it should be easy wiring.

    Good luck.
  8. amiller

    amiller Guest

    Wow you guys are really quick. Aleena is two years old, so most of
    what we are working on is basic cause and effect type stuff. She is
    only able to operate a single switch with each hand, and it's placed
    directly under her fingers. It's very sensitive and can trigger from
    the weight of just a piece of paper. It has a 1/8 in phone plug at one
    end allowing me to move the switch from toy to toy. Since she can only
    operate one switch I can only wire her toys to do one thing. My only
    idea was some way to cycle through the operations of a toy with each
    click or try to program some kind of pattern in the clicks of her
    switch so it can do different things.
  9. John B

    John B Guest

    I would use one large button and an AVR mega8 with a bunch of low
    current relays on the outputs. The whole thing can run from three AA
    cells. If you can find someone who can program a chip for you I'll
    write the code in a couple of hours. (Not just now as it's nearly
    midnight here).
  10. Joerg

    Joerg Guest

    Hello John,
    That would be the way to go. Especially since it can be made fancier as
    Aleena grows and learns.

    With a micro controller it is also much easier to include hold-time
    control some day. For example a short click would trigger one function
    while holding the same button for a couple of seconds triggers a
    different funtion. Or where a simultaneous push on both hands triggers
    yet another.

    Regards, Joerg
  11. bruce varley

    bruce varley Guest

    Some good postings on this already, IMHO they've honed in on the important
    point, that you should focus on a programmable system, preferably one that
    you can evolve yourself. Don't be scared of programming, anyone can do it,
    it's creative and can be fun. It would be useful if you can locate a
    friendly programmable device that you can get familiar with. For starters,
    try Feel free to email me with queries.

    . Remove em and dee to email.
  12. amiller

    amiller Guest

    I would love a programable device, I have a lot of experience with
    computer programming. Where can I find more information about this
    mega8 device and what kind of places would I go to look for purchasing
    these types of things.
  13. Tim Wescott

    Tim Wescott Guest

    If you're not big on electronics you can check out the basic stamp. If
    you're in the US you can get these at Rat Shack -- they sell a kit for
    around $90 that (I think) includes the PC host side stuff and
    everything. You'll have to program in Basic (yuck), but you won't have
    to learn lots of electronics or design a board or anything.
  14. John B

    John B Guest

    The mega8 is an Atmel part. A member of the AVR family of 8-bit RISC
    processors. Start at these two sites:

    The AVR is designed to be programmed in C, although you can use
    assembler, but I wouldn't recommend it. There are several cheap or free
    C compilers, as well as some expensive ones. GNU C is free, but the
    Imagecraft compiler is very reasonable and is the best value for money
    that I have found.

    Hope this helps.
  15. John B

    John B Guest

    Sorry, forgot to say that Atmel devices are available from Digi-Key or
    Farnell (which is Newark in the US).
  16. I've just posted this in another group:

    There is an organisation called "TASH" (Technical Aids & Systems for
    the Handicapped" ( that deals with
    this sort of thing. You may find something there to help you.

    About 10 years ago I designed a unit for the local Kinsmen Rehab group
    that could be controlled by one or two switches and scanned through 8
    functions. It was an improved version of a TASH product called a
    "Kincontrol". It had relay outputs, and just provided contact
    closures, so its outputs could be connected in parallel with the
    existing switches on your daughter's toys - no need for the device to
    provide (or care about) the toy's power requirements (as long as they
    don't exceed the relay contact ratings.

    Peter Bennett, VE7CEI
    peterbb4 (at)
    new newsgroup users info :
    GPS and NMEA info:
    Vancouver Power Squadron:
  17. Hal Murray

    Hal Murray Guest

    Digikey has Atmel's STK500 for $80.

    It comes with some AVR chip other than the Mega8. I forget which one.
    You can find out by reading the documentation. Anyway, if you really
    want the Mega8, order a few in DIP package.

    Digikey also carries the PICKIT1 from Microchip for $36. You might
    want to scan the documentation.
  18. quietguy

    quietguy Guest

    I reckon it would be worthwhile for you to contact some of the
    organisations set up for people with a disability - eg for those with
    cerebral palsy. IIRC there are LARGE-key keyboard available - these often
    only have 4 to 10 or so keys and the idea is you can plae a picture of a
    concept/item on a key and map that key to perform the appropariate action.

    Of course this depends on whether or not your daughter could select one
    key from (say) four in order to select an action/item etc

    Anyway - best of luck and good wishes to your daughter

  19. amiller

    amiller Guest

    Thanks for all the suggestions, you guys have been a huge help. I have
    a lot to look at.
  20. JosephKK

    JosephKK Guest

    Yow, you lit me up. My twin brother was institutionalized from the time he
    was 8 from severe cerebral palsy. I developed some gadgets for him, and
    learned of some low cost techniques for more gadgets. kinds only cheap for
    electrical engineer / good technician types though. (read parts cost only).
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