Need help with a Buzzwire game project

Discussion in 'General Electronics Chat' started by Billiam, Aug 24, 2014.

  1. Billiam

    Thread Starter New Member

    Aug 24, 2014
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    I am attempting to make a Buzzwire game project. This is a shaped metal rod that a person carefully navigates a circular wand without touching it. The goal is to reach the other side of the wire without touching the wand to the wire. If you miss the wire then it will make a buzzing sound.

    My objective is to make a large, human-sized curvy shaped stainless steel tube which will be mounted into the ground. The idea I have is to avoid wires and have all the electronics incorporated into the handle of the wand. I want to incorporate a speaker in it with a circuit that can detect metal to metal contact anywhere around the hoop. No optical devices, no proximity detectors but simply detect the increase of metal mass in contact. This will be used outdoors in the bright sun so it has to be rugged, battery-powered, possibly solar-rechargeable, durable and simple for less parts to break down.

    Any ideas how this can be accomplished? I am trying to find some way to not have it accidentally triggered. The hoop may be stainless steel as well. Any help would be appreciated.
     
  2. ISB123

    Well-Known Member

    May 21, 2014
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    I think you could use NE555 IC.

    PS

    Here is one using ne555,picture from internet.

    [​IMG]
     
    Last edited: Aug 24, 2014
  3. #12

    Expert

    Nov 30, 2010
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    That circuit touches in two places. If fastening the wand to the sculpture is a way to stop people stealing the wand, this is a good, simple, approach.

    I think the O.P. asked for something like a touch operated dimmer circuit where the oscillator is in the wand and contact with a large mass changes a frequency or a load to start the noise maker. My mind goes to an LM556 chip. One supersonic oscillator which, when loaded, allows the audio frequency oscillator to run.
     
  4. ian field

    Distinguished Member

    Oct 27, 2012
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    Without actually completing a circuit, you could energise the wire with a signal of a few kHz and make a "nearly deaf" receiver in the loop handle that only activates if it actually touches.

    Another route is to pinch the general idea of an inductance balance metal detector, instead of a search coil maybe a pair of 455kHz IFTs tuned to a specific beat frequency - which is detected by a LM567 tone decoder. Loop touching the wire throws one of the tuned circuits out of whack and the beat note swings out of range for the tone decoder.
     
  5. Billiam

    Thread Starter New Member

    Aug 24, 2014
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    Wow, you guys are great and thanks for the quick responses.

    #2: Love the versatile 555 timer but I do not want to have any wires connecting to the hand wand so that design is out. Security is not a problem since the idea is to put the substantial hand-held loop permanently around the rod. non-removable except for the electronics which can be built into the handle.

    #3: Interesting idea. Not sure how to do that yet though.

    #4: I like the metal detector idea. Perhaps a coil within the loop? Could you go further with your explanation? I think I got what your saying but need a bit more specifics for my understanding. Metal detectors use coils but the object they are detecting is typically below the coil and not inside the center of the coil. I am not sure how that could work.

    The idea is to make this coordinate trainer industrial so it can be put outside in a park for elderly people to use among other exercise equipment tailored for them. It has to be tough, withstand the elements and probably be recharged by the sun. I was going to incorporate a simple circuit that would turn it on when it is giggled (simple tilt sensor, tiny Arduino chip, insulated rechargeable battery and a flexible solar cell mounted in a clear polycarbonate cylindrical handle. The loop could be carbon fiber which is conductive (but coated with epoxy which is non-conductive). Perhaps that could be used somehow. We are on the right track though with the non-contact, no wire design.
    ----------------------------------------------------------------
    I found a simple explaination of a metal detector here:
    http://www.indepthinfo.com/gadgets/metal-detector.shtml

    "The disk on the end of a metal detector is actually a coil of metal inside a plastic case. A pulse of electricity is sent through it from a power source. The electric pulse creates a magnetic field which is projected all around it. Even as an electric current can create a magnetic field, a magnetic field, when it comes in contact with metal can create a current.

    Just so, when the magnetic field (created by the coil) passes through a bunch of coins (or any other metalic item) it creates a current in them - these currents are known as Eddy Currents. They, in turn, create their own magnetic field, affecting the metal coil in the metal detector (actually creating an opposite current to the pulse). Sensors detect this opposite current and send a warning signal to the operator of the metal detector either through light or sound."
     
  6. #12

    Expert

    Nov 30, 2010
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    It doesn't matter whether the object being detected is under, over, or around the sensor. It's about proximity, not direction. And, we were all assuming the loop on the wand would be stainless steel...weren't we?

    The 556 idea (mine) is a cruder form of Idea #3. If it works, it's simpler and cheaper. Problem is, it has to be adjusted to the right frequency and load impedance for THIS object. Once you get that right, the same values will work for all similar sculptures. A full blown metal detector will find the object, no matter what size it is (at least as big as a penny).

    Here's a block diagram of the 556 design:
     
    Last edited: Aug 24, 2014
  7. Metalmann

    Active Member

    Dec 8, 2012
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  8. Metalmann

    Active Member

    Dec 8, 2012
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  9. #12

    Expert

    Nov 30, 2010
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    "Operation" is the same as post #2
     
  10. KJ6EAD

    Senior Member

    Apr 30, 2011
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  11. Billiam

    Thread Starter New Member

    Aug 24, 2014
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    I grew up with that toy and that was my original inspiration. Also it's the only kind I have had experience with. You tuned into that pretty quick.

    So you are saying that the dual timer could be used to generate a high frequency oscillation on one side of the chip, which by proximity to a metal mass reaches a threshold to trigger the audio oscillator with the other half of the timer chip? And I probably don't need a coil with this design but to utilize the metal loop instead? If I understand this right then this design sounds simple. I would like to experiment with that. I might have that chip laying around. I know i have a few 555's crawling around.

    For lazy convenience anyone find a specific schematic that will do that as a starting point? I am crude with my electronic designs and more experienced with wiring and soldering. I expect I can calculate that from the formulas and plethora of 555/556 circuits on the internet. Wow, thanks again for the help. This is my first time on this forum and "bam" many helpful replies.
     
  12. Billiam

    Thread Starter New Member

    Aug 24, 2014
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    #10: Possibly. Another good idea. Two circuits instead of one but I get where you are going with that. Inject a signal up the squiggly rod and catch it with the hand wand. Interesting.
     
  13. ian field

    Distinguished Member

    Oct 27, 2012
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    The metal detector suggestion is just a general idea - you don't actually use search coils, but tiny IFT cans like in the back of an AM transistor radio.

    You can get the bulk of the circuit diagram from metal detector projects on the web.

    The 2 IFTs are contained inside the handle and are tuned to similar but different frequencies - the 2 frequencies mix together and produce a lower frequency beat note, you tune the 567 to detect that tone.

    The hoop that follows the wire is loosely coupled to one of the IFT tuned circuits, so if it touches a mass of metal it throws the oscillator out - the beat no longer is in range for the 567 and you get a detection.
     
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