I think any analog DAQ based solution will be expensive. Use too many analog levels, and it will not be accurate. Use a small number of levels, and the price per port for analog connection will drive the price too high.
You can try using computer mice. cheap 2 button+scroll wheel starts at 17NIS on zap. Such a mouse can provide at least 5 events: right button left button middle button (scroll wheel press) scroll up scroll down You can then take apart the mouse and repackage it, maybe replacing the wheel with 3 distinct switches. Ofcourse you might need powered hubs if you intend to drive 30 mice. You could try taking eight 4 port unpowered hubs (also starts at 17 NIS on zap), and if you computer has 8 free USB ports (many do these days), you could fit 30 mice, and hope that each port can drive 4 mice + hub. You will also have 2 spare ports (8*4-30)for the console keyboard/mouse. Another direction would be to use an arduino board. http://www.seeedstudio.com/depot/microcontrollers-arduino-compatible-c-132_133.html The cheapest $19 board has 14 digital inputs plus 6 analog ones which you can treat as digital if you like. 20 input pins can serve 5 users (4 input pins/user) or 6 users (3 input pins per user if you wire them smartly - 1 qualifier signal that is grounded by all 4 switches, and 2 more that are getting a 2-bit binary code. seeedstudio has free worldwide shipping for orders above $50. Udi 2011/4/6 yosi yarchi <yosi.yar...@gmail.com> > Hi > > This is interesting idea. However, it support voting between 2 options, > only, while I need at least 4 options. > I thought that combination of analog DAQ and 4 push buttons with analog > output may help here. > Does someone have an idea about such combination (analog DAQ+edge unit)? > > With best regards > Yosi Yarchi > > > > > > On 04/06/2011 10:55 AM, Jason Friedman wrote: > > I think the best solution would be to use a data acquisition device, either > USB or PCI. > > Measurement computing sell relatively cheap devices, e.g. this USB one > for $99: > http://www.mccdaq.com/usb-data-acquisition/USB-1024-Series.aspx > > can measure 24 digital channels (you could get two if you need 30). > > Each "competitor" could have a small switch, which connects their input > line to say a 5V power supply. > > You can then write a very simple program to detect when each competitor > presses their switch > (with sub-millisecond accuracy!). > > These devices apparently have linux support. > > Jason > > On Wed, Apr 6, 2011 at 2:44 PM, yosi yarchi <yosi.yar...@gmail.com> wrote: > >> Hi all >> >> >> I need application that will be able to collect and process inputs from 30 >> (!) competitors, and will display the results very fast. The ideal solution >> could be to collect the inputs via SMS: each competitor send his answer, the >> application collect the answers (related to phone number) and process them. >> However, I can't assume that the competitors have mobile phones (they may be >> little childs...). >> >> >> I thought to use 30 USB numerical keyboards as input devices, connected >> with cables to 3 hubs, connected to the computer. >> >> However, I don't have experience with USB drivers at linux... >> >> >> Is it feasible? What should be the main guidelines for the solution? >> >> >> With best regards >> >> Yosi Yarchi >> >> >> >> _______________________________________________ >> Linux-il mailing list >> Linux-il@cs.huji.ac.il >> http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il >> > > > > -- > Jason Friedman > Postdoctoral scholar > Macquarie Centre for Cognitive Science > Macquarie University, NSW 2109 Australia > email: write.to.ja...@gmail.com > web: http://curiousjason.com > > > > _______________________________________________ > Linux-il mailing list > Linux-il@cs.huji.ac.il > http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il > >
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