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Please double check my circuit for me (and make sure i don't get electrocuted)

  1. Jun 7, 2010 #1
    Hi everyone! So these forums have been great help to me as I've gone through the beginning stages of my design process and begun choosing components for my project. Thus, I figured I'd enlist your help to look over my first rough design draft.

    A little about the project: The overall idea is to create a stage lighting effects box for my band. How I've decided to do it is in two parts:

    First I'll connect a Xbee via UART to my computer using this: http://www.sparkfun.com/commerce/product_info.php?products_id=9111 ...and I'll use matlab to interface and send commands over the xbee.

    The second part is a box with an Xbee to receive the commands, which then sends the data to a microcontroller, which switches on and off the correct electrical outlet (of which there are four). Plugged into these electrical outlets will be all kinds of stage lighting (such as a strobe light, siren light, black light and yellow light).

    The second box will look something like this:
    [PLAIN]http://midtownmunch.com/setup.jpg [Broken]

    This part of the project (the second box with the four outlets) is the part I could use design help with. So far, this is what I have for a very crude schematic:
    [PLAIN]http://midtownmunch.com/circuit-diagram.jpg [Broken]

    Since I've never worked with any of these specific components before, I would love someone whose familiar with Xbees and microcontrollers to make sure that those connections are correct and I have everything I need. Same thing for the relays (this is the part I'm most nervous about, since they control a lot of power).

    More about the specific relay I intend to use can be found here: http://www.sparkfun.com/commerce/product_info.php?products_id=101
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Jun 7, 2010 #2


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    At first glance; you're not going to get 33 volts from a 5 volt regular. Probably just a typo?

    Otherwise I think you have the right idea. My concern is that you use proper wiring techniques when working with the mains.

    Edit: I'm for familiar with the ATMEGA16B however.
    Last edited: Jun 7, 2010
  4. Jun 7, 2010 #3
    Oh crap, that should be 3.3, not 33. My bad--fixed. Did you mean you're -not- familiar with the ATMEGA168?

    Making sure I use proper wiring techniques when working with the mains is my concern, too. If you see anything wrong with my schematic, or just have any tips/tricks, please let me know!
    Last edited: Jun 7, 2010
  5. Jun 8, 2010 #4


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    Yea. My bad. I'm not familiar with the ATMEGA168.

    Make sure that you have the metal box grounded to the mains ground.
  6. Jun 8, 2010 #5
    What about using a plastic box -- or is that a really bad idea?
  7. Jun 8, 2010 #6


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    You need a fuse in your hot input lead. You show the Hot and Neutral slots of the outlets backwards. (The small one is the hot slot; the longer one is the Neutral slot.)

    And as Don says, you need to connect the ground wire of the input plug to the metal body of your enclosure. It needs to be connected with a secure screw or stud.

    Your AC Mains wiring inside needs to be very securely done, with little chance of loose connections. I'm not real comfortable with your level of knowledge so far on this project -- is there anybody near you who is familiar with the NEC (national electric code) and common practices for devices that would generally get UL approval?
  8. Jun 8, 2010 #7
    A fuse is a really good idea -- I was thinking about adding one. Do you know of any good fuses (digikey preferably) for this project?

    I'm definitely aware that if I use a metal enclosure I'll need to ground it -- I was wondering if I could use a plastic enclosure instead, or if that was a bad idea?

    For the AC main wiring, it'll be screwed and soldered in place, and then I will wrap electrical tape around the whole outlet. It should be pretty secure. I am also not that confident with working with such high power, but no I don't know anyone around me who is familiar with the NEC or knows anything about common practices for UL approval. I think if I put a fuse in there, use a grounded metal box, and solder/tape/twist all the wires into place on the mains, though, it shouldn't be a huge problem. Also, I'll probably plug the actual power wire to the box (the one providing power to the 4 main outlets) into a GFI in my wall (instead of a regular outlet) for added safety when I use it.
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