cycle~ polarity.

i may be a little out of my depth here so excuse me if my terminology is wrong.

i have been trying to build a simple chorus from scratch as a learning curve. i am using a cycle~ to modulate the delay time but have noticed that cycle~ is bipolar, so if i have a delay time of 50ms it modulates from 0 to 50 then to -50. this wont do and i would like to know how to make cycle uni-polar? am i using the right terms?

i have been trying adding numbers to the signal to make it higher than zero but i dont get the results i'm after.

thanks for the helps.
ned
:)