Buzz wire game design

[inspire]

Hi everyone, I need help as I am trying to make a circuit for a buzz wire game, the type where you need a steady hand as you move the loop along a wire pathway trying hard not to touch the wire, setting the buzzer off.


The big difference with my one is that I need it to be wireless! I don’t want the hand held loop to have a wire connected to it, it will just be a metal ring held in the hand of the user. The circuit must run on batteries, so no high voltage, say around 3V to 6V (or maybe slightly higher)

There are only 2 ways I can see of doing this:

1. Using a very sensitive circuit which relies on the user creating a ground/Earth by touching it, although having such low voltage in the circuit this may be difficult, or

2. The wire that the loop moves across would have to be made of something really intricate, which has lots of small copper lines on it, so that when the loop touches it, it will complete the circuit?

Any ideas or suggestions for another method or solving this problem would be greatly appreciated!

Many Thanks

Inspire

 

[Gryd3]

Try a touch sensor... Old lamps can pull it off quite well... but the sensitivity will vary depending on the user. I can just barely touch my phone's screen or a touch-on lamp and have it work, but my younger brother needs to press his finger to it.
Some experimentation may be required. An intricate wire method like you mentioned may be difficult to construct and maintain.

Are you opposed to having an 'active' wand that would buzz or vibrate?

 

[inspire]

Thanks Gryd3, I like the idea of the touch lamp as they need only a finger touch, but aren't these mains voltage? I agree an intricate wire would be difficult to produce.

I would rather have a plain metal loop than an active buzzer as I want to keep the wand very basic and simple.

Thanks for the good advice

 

[Gryd3]

Thanks Gryd3, I like the idea of the touch lamp as they need only a finger touch, but aren't these mains voltage? I agree an intricate wire would be difficult to produce.

I would rather have a plain metal loop than an active buzzer as I want to keep the wand very basic and simple.

Thanks for the good advice

The wand would need to be conductive, the wire loop that you are making would be a sort of touch sensor. The lamp was brought up as an idea to get the idea across. The same concept can be accomplished with a battery operated device.

The touch sensor uses a change in capacitance to detect a 'touch'. The wand may be tailored to provide this, or the metal housing could simply allow the human operator's body to do this. Another real-world working example are the capacitive stylus pens that are being sold for iPhone/Android and other smart phones. The screen detects the want the same way it detects a finger.

The next questions are:
How are you with electronics?
How deep do you want to go? (Build lots yourself, or buy pre-made modules and wire them together)

 

[inspire]

Yes, I have just been reading some interesting stuff online regarding these touch lamps.

I am trying to build a prototype to prove that the concept works so this would be a one off construction for now so I am not concerned how bulky it would initially look, I just need it to run on batteries. I have a very basic understanding of electronics so could put this thing together if need be.

I'm thinking a good way would be trying to find an existing battery type touch lamp and taking it apart and using this to mock up the prototype? Although these are not as common to find as the mains driven ones.

Any ideas of a basic product using this principle I could take apart and use?

Many thanks

 

[Gryd3]

Are you required to have a fast turn-around?

You can buy ICs specifically tailored to detecting touch like this : http://www.atmel.com/Images/Atmel-9543-AT42-QTouch-BSW-AT42QT1012_Datasheet.pdf

Or there are tricks you can employ with a microcontroller like a PIC, AVR, or Basic Stamp.

It is a very low component count project, the only issue I can see it the sensitivity of the sensor. This will need to be tweaked a little to prevent false positives, but also be sensitive enough to detect a light touch. (This can be done with a simple trim-pot once the structure is made. You may need to build in some type of auto-compensation, as external factors may change the results like humidity)

Edit: The spec sheet I found may not be ideal, as it tries to compensate for brief inadvertent touches. Other part numbers may be available.

 

[inspire]

Great work!, will look into this. Thank you for your help.

 

[Gryd3]

Not a prob. Let us know when you're ready to experiment

 

[JimW]

Another direction entirely might be a simple metal detector circuit. Your hand held metal wand will change the resonant frequency of the sense loop (which your metal wire frame would be part of). It is not detecting the metal of the wand, it is changing frequency due to your body capacitance.

The biggest problem with this approach is that the simple circuits tend to drift. So you would have to null it out before playing. The advantage is that a circuit like this can be made with a single quad CMOS NOR package.

-JimW

 

[Arouse1973]

Another direction entirely might be a simple metal detector circuit. Your hand held metal wand will change the resonant frequency of the sense loop (which your metal wire frame would be part of). It is not detecting the metal of the wand, it is changing frequency due to your body capacitance.

The biggest problem with this approach is that the simple circuits tend to drift. So you would have to null it out before playing. The advantage is that a circuit like this can be made with a single quad CMOS NOR package.

-JimW

Good Idea Jim. I would have thought the circuit the circuit could be made stable by using a crystal. And then maybe pull the crystal of frequency by touching the metal loop then using a simple F to V could detect this.
just a thought
Adam

 

[Gryd3]

Seems as thought the ideal solution is still to use the capacitance of a human to alter the circuit in the Wire maze.
I am curious though which one would be more robust and reliable.

Does anyone have any reason to believe that adding a capacitor to the wand would help exaggerate the effect of a human touching the wire? This could help make the buzzer more reliable if it works like this, but it's only a guess of mine right now.

 

[inspire]

Great info everyone. I am not an electronics whizz kid but know how to solder a circuit together, so has any one got any suggestions of a circuit that I could try. I won't blame anyone if it doesn't work as it is all part of the fun of triall and error! Or any suggestions of a product that I could take apart and modify?

I want to keep the wand just a metal loop with no added extras as this part is crucial to the design.

Thanks all

 

[Arouse1973]

Hi Inspire.
If I get time this week I will have a look for you. I am on holiday all week and have a few things to do. Someone might beat me to it though.
Adam

 

[inspire]

Have just found a selection of touch sensitive 555 timer circuits on Youtube which look promising so will give these a go and report back, many thanks everyone, any new suggestion are still welcome!

 

[Gryd3]

Sounds like a great venue to try first.
I have been digging through some datasheets for capacitive touch controllers, and they all appear to have a 'de-bounce' in them to prevent false touches caused by brief inadvertent touches... but this is what is desired so these chips may not work for us.
Keep us posted on the 555 circuits. The 555 is a great IC to learn and is capable of an incredible amount. You can also build a touch sensitive circuit with a microcontroller but they cost a little more. You wither need to pay extra for an Arduino, or pay a little extra for a programmer for many of the other ICs. There are also the other options above.

 

[inspire]

Hi all,

Have found a circuit that almost does the job, the only problem is that it is very temperamental in that it sometime it works and then sometimes it doesn't. Sometimes the LED comes on for the right amount of time and then other times it stays on too long! I have noticed that if any static gets near it, it will go off too!

I have changed the electrolytic capacitor to a 10uf instead of a 100uf as this seems to help shorten the time the LED stays on for as I only want it to come on and off quickly.

Any suggestions how this circuit could be made more stable, I also would like to have a buzzer connected to if any one can help or if anyone has a better circuit, I'm all ears!!

Thanks

 

[Gryd3]

Hi all,

Have found a circuit that almost does the job, the only problem is that it is very temperamental in that it sometime it works and then sometimes it doesn't. Sometimes the LED comes on for the right amount of time and then other times it stays on too long! I have noticed that if any static gets near it, it will go off too!

I have changed the electrolytic capacitor to a 10uf instead of a 100uf as this seems to help shorten the time the LED stays on for as I only want it to come on and off quickly.

Any suggestions how this circuit could be made more stable, I also would like to have a buzzer connected to if any one can help or if anyone has a better circuit, I'm all ears!!

Thanks

Because of the nature of how that product operates, it will be susceptible to things like static and other external factors.
Connecting a buzzer is fairly easy. If you connect a transistor to the same wire that the LED is on, the transistor can be used to control a buzzer.
As far as stabilizing your project is concerned. Adjustments can be made to make it less sensitive, but you will reach a point where it will no longer reliable pick someone up. If an adjustment can't be found that works well, the circuit will need to be modified to either include a microcontroller, or other components to help detect more sudden changes like touch instead of more subtle changes like static.
If you wan't to finely control the LED or buzzer output duration, the only thing I could think of is using a 555-timer setup as a one-shot. Once triggered, it will stay on for time you have set then go out again.

 

[inspire]

I forgot to mention what circuit I was using, here it is:

Thanks again for your advice Gryd3