Pedal Power Bicycle Generator Fun in The Classroom
This LabVIEW graphical user interface monitors two pedal power bike generators simultaneously. The LabVIEW screen shot below shows the case of when one bike is driving the other. (Keep in mind that the generators used are really just regular DC permanent magnet DC motors).
In interesting experiment to show people is to let one person ride one of the generators while the 2nd generator does not have any one riding on it at all. The two pedal power generators are connected to each other. Because the generators being used are also permanent magnet DC motors, the one bike making the electricity powers the other bike which uses the electricity.
The way this works is shown below where bike 1 is being driven (the YELLOW line on the chart below), while the other is unmanned. The motor on bike 1 is acting like a generator, while the motor on bike 2 is acting like a normal motor. That's why the 2nd LabVIEW graph showing the current has two symmetric waveforms- reflecting each other. The blue wave form shows the negative current to the unmanned generator which now becomes a regular DC motor.
Of course if you put a Diode in the circuit this phenomena would no longer happen. The diode would only allow the current to flow in one direction. You would use diodes when both bikes are being used to charge deep cycle battery or some other load. That way a person could get off the bike to take a break and it wouldn't suck the power from other people.
LabVIEW data acquisition using LabJACK data acquisition box Order Information HERE
More information and screen shots for this software HERE