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Large Wire Buzzer game

Discussion in 'General Electronics Discussion' started by AshSplash, Aug 20, 2016.

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  1. AshSplash

    AshSplash

    10
    1
    Dec 9, 2015
    Hi guys,

    I'm building a large wire buzzer game for a village fair. It's a wooden box with with a wiggley 8mm copper pipe for the wire and hoop.

    I'm looking at buying these for the "alarm":
    http://m.ebay.co.uk/itm?itemId=172203759436&varId=471036939041

    http://m.ebay.co.uk/itm?itemId=152003496191

    These will be connected in series with the power supply, the hoop and the wire so when the hoop touches the wire it completes the circuit.

    I'm not sure about the power supply though, the LEDs are 12v and the buzzer would be fine on 12v but I'm not convinced a square 9v battery and two 1.5v batteries would cover be sufficient for the full day at the fair and with all the resistance in the copper pipe.

    I do have two 18v dewalt drill batteries (which seem to actually deliver 20v). I'm thinking these would last the day and give the power needed. However I'm guessing this would kill the LEDs? Would this solve the issue? http://m.ebay.co.uk/itm?itemId=261753222452

    Thanks for your help!
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,501
    2,841
    Jan 21, 2010
    Firstly, the copper tube has a very low resistance.

    Secondly, batteries of different types in series is a bad idea, and you're right in thinking the capacity may be too low.

    I would suggest an SLA 12V battery, but the battery you mention sounds fine.

    The buzzer is not a real problem because it can handle a wide voltage range.

    The LED strip is another matter. These are very poorly designed for their stated purpose, but can be successfully used with a constant current driver. Never the constant current driver will require some voltage overhead. If your battery maintains a voltage above 14V you should be fine, however if it drops below this (even with a constant current driver) the current through the LED strip will start to fall.

    I suspect that your Dewalt batteries are lithium based and will vary in voltage significantly as they discharge.

    Our LED resource has some simple constant current drivers for LEDs which would be suitable for your application.
     
  3. AshSplash

    AshSplash

    10
    1
    Dec 9, 2015
  4. AshSplash

    AshSplash

    10
    1
    Dec 9, 2015
    It occurred to be I may be over complicating things, I'm probably better off getting an LED light that can handle the batteries as they are e.g. http://www.ebay.co.uk/itm/160994283365 they say they work with 12 or 24v so I'm guessing 18v would be fine?
     
  5. AshSplash

    AshSplash

    10
    1
    Dec 9, 2015
    Went ahead and bought the light that could handle the batteries as is, will post a photo when it's complete!
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,501
    2,841
    Jan 21, 2010
    Hmmm, it says 12 or 24V, not 12 to 24V. But hey, it might work.

    I tried to look at the item earlier but it wouldn't come up on my phone.
     
  7. AshSplash

    AshSplash

    10
    1
    Dec 9, 2015
    Thanks Steve, I asked the seller who said "it would be fine at anything between 12 and 24 so 18v would be fine."
     
    (*steve*) likes this.
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