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Compact DC SSR for LED Canes

Discussion in 'The Development Lab' started by David_AVD, Dec 26, 2010.

  1. David_AVD

    David_AVD Bite my shiny metal ass!

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    I've bought a bunch of the Kmart 71cm candy canes. They are empty (no lights), but come with a ground stake that has the wiring channels built in. These canes seem to be a good size to insert (LED) lights into, and IMO would look great when at least 6 - 8 are used together.

    Now, what I plan to do is design a small controller PCB to fit into the base of each cane. It would have DMX input and each one would be individually addressable to allow for some more detailed sequences. I also plan to add cable tails to each with the male end being input and the female being the output / loop through.

    Driver chips tend to come in 8 or 16 output counts. Some preliminary LED placement tests show that 8 LEDs may not be enough to fill the tube well, but 16 is probably too many. So, maybe a 16 output driver with only 10 or 12 actually used may be the best option. I have thought about driving the LEDs directly from a PIC chip, but power dissipation could be an issue. Using a driver chip also means the power supply can be higher than 5V.

    I have thought about breaking the design up into two boards; one for the DMX input and processing and the other for the LED driver. This would possibly reduce the overall cost, but means that you'd need to have a separate control box between the DMX stream and the first cane. It may also require more wires between canes than DMX would use. I do like the idea of DMX controlled elements that don't need external support electronics.

    I did try fitting some WS2801 pixels into the canes as they are a great price per node, even if you only used the red portion. The main problem is that I think the 4 wire flat cable will cause quite a shadow in the tube. I don't have a 2801 controller handy at present to confirm this though. You'd also need to run the end of each section back to the base for feeding to the next cane which will add yet more shadows.

    Anyway, these are just my musings on the subject. Sometimes it's good to write these ideas up publicly and get comments before committing to a specific course of action! :)
     
  2. kevr

    kevr Full Time Elf

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    Sounds like a great idea to me, I spotted these in Kmart a couple of months ago and bought a load of them for a rainy day. I have just left the Kmart boxing day sale to see what was there and got a few more LED's but no more candy canes.

    I will be watching with anticipation to see what you come up with.

    Kev :)
     
  3. Superman

    Superman I Have C.L.A.P and its very infectious Global Moderator

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    You are the Master David. sounds good
     
  4. OP
    OP
    David_AVD

    David_AVD Bite my shiny metal ass!

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  5. cenote

    cenote Suburbs of Philadelphia

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    Any chance you could post a pic of the guts? I am guessing you just bread boarded something?
     
  6. OP
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    David_AVD

    David_AVD Bite my shiny metal ass!

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    I rarely use breadboard these days. Usually PCB first go for any project. The PCB is at work so can't take a picture just now. Sorry.
     
  7. chilloutdocdoc

    chilloutdocdoc Full Time Elf

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    So how many channels can the 2803 drive?
     
  8. OP
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    David_AVD

    David_AVD Bite my shiny metal ass!

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    The WS2803 is very similar to the WS2801, except it has 18 outputs.
    Data sheet is here: http://www.users.on.net/~avd/acl/WS2803.pdf
     
  9. Blickensderfer

    Blickensderfer Ohio, USA

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    David,
    To bring this topic back up. I would be interested in 84 plus a couple spares after your redesign. In my setup, the PCB doesn't have to fit up inside the candy cane.
    Thanks,
    Dan
     
  10. OP
    OP
    David_AVD

    David_AVD Bite my shiny metal ass!

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    Here's what the current board looks like:

    [​IMG]

    [​IMG]

    I could look at an updated version (so the regulator can sit on the top side) and offer them here as a board only buy.
     
  11. XDU

    XDU Full Time Elf

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    I'd certainly be interested in some if you make them public David
     
  12. Timon

    Timon Apprentice Elf

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    What regulator are you using?
     
  13. OP
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    David_AVD

    David_AVD Bite my shiny metal ass!

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    It's an OKI-78SR-5/1.5-W36-C switchmode unit.
     
  14. JPB

    JPB Full Time Elf

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    David, are you going to stock these and if so do you have a rough idea of price?

    I am thinking of redoing my candy canes for 2012 so that I can run them as normal candy canes or as vu-meters (I think that is what they are called) .

    Jon
     
  15. OP
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    David_AVD

    David_AVD Bite my shiny metal ass!

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    I'll be revisiting this design in the new year, so will advise once I've got something nailed down.
     

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