Why not try something simple like the sin function as the training data? Since you are comparing the training methods and don't really care about what you are training the network for, it should work and be easy to generate the training data.
Train the network using sin(x) where x is the input and the output is the value of the function. An added benefit in your case is that the absolute value of the result is already in the range 0-1. It would equally work with other mathematical functions.