Hey guys how's it going this is my first post so take it easy on me . I'm in my last year of electrical engineering technology and we need to design and construct a final project. On the list of possible topics was the idea of a bio-med game interface. It would be biomed probes detecting muscle activity to control a video game. This idea was badass, so of course I wanna get all over it. Rather than getting an open source game, rewriting the code, building a cable to connect it to the computer, and etc I found an old think geek DIY pong game.

http://www.thinkgeek.com/geektoys/science/8546/
(avaible via partsexpress.com)

So I want to replace the buttons with connector probes attached to circuitry. I figured I'd use a transitor so that when you flex your arm it would produce enough voltage to the base to act as a switch closing the switch on the board. I'm great with the amplificiation of volages, transitors, and such. However if anyone can any point me to where I would purchase biomed probes and any documentation you might know of it would be much appreciated. Also when I finish I'll post it up to the site with video of badass 1 on 1 pong.

 

I just put my multimeter on my arm's muscle and flexed it. The voltage was nearly nothing, much less than the 0.6V needed by the base of a transistor.
You will need a high gain opamp circuit to boost the muscle's voltage to a useable level. The high gain will pickup mains hum which will saturate the opamp unless its inputs are balanced and shielded.

__________________
Uncle $crooge

 

Oh definately I know that. It would only be milivolts, however I would setup an amplifier circuit (probably 741 op-amp) to amplify it as much as I could without background noise before it goes to the transistor.

 

Some random links:

http://www.analog.com/library/analog...term=emg&la=en
http://www.analog.com/en/app/0,3174,...5F1132,00.html
http://www.analog.com/UploadedFiles/...term=ecg&la=en

http://focus.ti.com/docs/solution/fo...print/272.html
http://www-s.ti.com/sc/psheets/slaa280/slaa280.pdf

 

Don't use a very old and very noisy 741 opamp. Use a much better instrumentational amp IC or better ordinary opamp.

__________________
Uncle $crooge

 

A little off subject, but have you seen this pong game?
http://www.cyberniklas.de/pongmechanik/indexen.html

Mechanical pong, inplimented with relays and analog sound. real retro, 1940s style. Check out the video of it working!

 

Just as a followup I did construct this project and got it working great. If you are interested in seeing how it turned out check out http://teckjunkie.com/wiki/

 

Get some of the connectors used for electrocardiogram (EKG or ECG) recording. They are approved for humans, cause minimal skin reactions, and provide good electrical contact that is relatively insensitive to noise from mechanical movements per se. John