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Large Wire Buzzer game

AshSplash

Dec 9, 2015
10
Joined
Dec 9, 2015
Messages
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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!
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,505
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Jan 21, 2010
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25,505
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.
 

AshSplash

Dec 9, 2015
10
Joined
Dec 9, 2015
Messages
10

AshSplash

Dec 9, 2015
10
Joined
Dec 9, 2015
Messages
10
Went ahead and bought the light that could handle the batteries as is, will post a photo when it's complete!
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,505
Joined
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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.
 

AshSplash

Dec 9, 2015
10
Joined
Dec 9, 2015
Messages
10
Thanks Steve, I asked the seller who said "it would be fine at anything between 12 and 24 so 18v would be fine."
 
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