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Sequencing LEDs for Historical Reinactment Model — Parallax Forums

Sequencing LEDs for Historical Reinactment Model

ArchiverArchiver Posts: 46,084
edited 2003-04-20 22:52 in General Discussion
Hi,
I'm a sculptor working on a piece which looks reminiscent of a model found at
the natural history museum. I have only a very basic knowledge of electronics
and was hoping for some advice. The piece I'm currently working on is a
table with a landscape model on top and a number of lines of LEDS running
across the surface depicting movement along trails. I'm trying to use a stamp
to trigger each sequence which will consist of an individual line of LEDs. As
each line lights however, the leds need to light one at a time and pause for
about one second before the next one in line lights. They will all remain lit
until the line is complete and then all turn off at once. I wasn't sure if there
was
a way to just use a series of capacitors between each light so that only one
trigger on the stamp handles the whole line, or if there's a much better
solution. A friend mentioned some sort of chip, maybe a cascade?, that
performs this function and said I should post here t try to find out a name or
if
this really exhists. The other question is that, I'm hoping to be able to make
each of the lines run as described above but both forwards and backwards
through the line. I'd really appreciate any help, suggestions or research
referances anyone could offer. Thanks, Ryan Taber

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2003-04-20 16:32
    This is certainly the sort of problem that could be solved with only a
    handful os discrete components (caps, resistors, transistors, etc), but
    as you are a scupltor and not an EE, I don't think you want to take that
    route [noparse];)[/noparse]

    The Stamp is, IMO, ideally suited for projects such as yours. You can
    drive LEDs directly from the stamp pins (with a current-limiting
    resistor of course). Your progam would probably only be a dozen or so
    lines of code... along the lines of HIGH 1, PAUSE 1000, HIGH 2 PAUSE
    1000...

    On Sat, 2003-04-19 at 18:53, grillgasher wrote:
    > solution. A friend mentioned some sort of chip, maybe a cascade?, that
    > performs this function and said I should post here t try to find out a name or
    if
    > this really exhists. The other question is that, I'm hoping to be able to
    make
    > each of the lines run as described above but both forwards and backwards
    > through the line. I'd really appreciate any help, suggestions or research
    > referances anyone could offer. Thanks, Ryan Taber
    >
  • ArchiverArchiver Posts: 46,084
    edited 2003-04-20 22:34
    Ryan,

    What you want to do is easy. While there are ways to do it without a Stamp,
    these need a working knowledge of electronic. And even then, it wouldn't be
    as flexible and easy to make "just how you like it".

    If you are controlling a lot of LEDs, more than a Stamp has pins for, you
    will want a shift register such as the 74HC595. Download the Stampworks1.2
    from the Parallax site, experiment 21 and 21b show how to use this chip,
    very easy. Basically it allows you to control many LEDs with only 3 pins
    from the Stamp.

    Another point regarding how many LEDs you want. If the total current draw
    exceeds the Stamps capabilities you will want something like a ULN2003. I
    think the Stampworks1.2 has information on using these as well. This chip is
    rated for more current than the Stamp, and is used to "heft the load".

    Hope it all works out,

    Jonathan

    www.madlabs.info



    Original Message
    From: "grillgasher" <ki_ct@h...>
    To: <basicstamps@yahoogroups.com>
    Sent: Saturday, April 19, 2003 3:53 PM
    Subject: [noparse][[/noparse]basicstamps] Sequencing LEDs for Historical Reinactment Model


    > Hi,
    > I'm a sculptor working on a piece which looks reminiscent of a model found
    at
    > the natural history museum. I have only a very basic knowledge of
    electronics
    > and was hoping for some advice. The piece I'm currently working on is a
    > table with a landscape model on top and a number of lines of LEDS running
    > across the surface depicting movement along trails. I'm trying to use a
    stamp
    > to trigger each sequence which will consist of an individual line of LEDs.
    As
    > each line lights however, the leds need to light one at a time and pause
    for
    > about one second before the next one in line lights. They will all remain
    lit
    > until the line is complete and then all turn off at once. I wasn't sure if
    there was
    > a way to just use a series of capacitors between each light so that only
    one
    > trigger on the stamp handles the whole line, or if there's a much better
    > solution. A friend mentioned some sort of chip, maybe a cascade?, that
    > performs this function and said I should post here t try to find out a
    name or if
    > this really exhists. The other question is that, I'm hoping to be able to
    make
    > each of the lines run as described above but both forwards and backwards
    > through the line. I'd really appreciate any help, suggestions or research
    > referances anyone could offer. Thanks, Ryan Taber
    >
    >
    > To UNSUBSCRIBE, just send mail to:
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    > from the same email address that you subscribed. Text in the Subject and
    Body of the message will be ignored.
    >
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    >
    >
    >
    >
  • ArchiverArchiver Posts: 46,084
    edited 2003-04-20 22:52
    And, if you have more than 12 LED's, you can
    expand the number you can drive with a simple
    74HC595 circuit. See Phillips website.

    BTW, the typical value for current-limiting resistor
    should be 470 ohms -- especially if you want to drive
    all 10.

    --- In basicstamps@yahoogroups.com, Brian <stamp@k...> wrote:
    > This is certainly the sort of problem that could be solved with
    only a
    > handful os discrete components (caps, resistors, transistors, etc),
    but
    > as you are a scupltor and not an EE, I don't think you want to take
    that
    > route [noparse];)[/noparse]
    >
    > The Stamp is, IMO, ideally suited for projects such as yours. You
    can
    > drive LEDs directly from the stamp pins (with a current-limiting
    > resistor of course). Your progam would probably only be a dozen or
    so
    > lines of code... along the lines of HIGH 1, PAUSE 1000, HIGH 2 PAUSE
    > 1000...
    >
    > On Sat, 2003-04-19 at 18:53, grillgasher wrote:
    > > solution. A friend mentioned some sort of chip, maybe a cascade?,
    that
    > > performs this function and said I should post here t try to find
    out a name or if
    > > this really exhists. The other question is that, I'm hoping to
    be able to make
    > > each of the lines run as described above but both forwards and
    backwards
    > > through the line. I'd really appreciate any help, suggestions or
    research
    > > referances anyone could offer. Thanks, Ryan Taber
    > >
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