Are all 3.5mm jacks the same in electrical power output?

Long version: I have a Nikon D7100 DSLR and though it has a built in intervalometer, it can take a maximum of only 999 images. I would like to use an intervalometer app on my iPhone 4s that sends a signal to a third-party device through the iPhone’s 3.5mm output, only without purchasing this this third-party device. I have a Cactus V5 wireless flash system which doubles as a cordless shutter fire remote if a cord is run from the 3.5mm output on the Cactus V5 to the GPS jack on the camera. My thought was to use this 3.5mm-GPS jack cord to connect my iPhone directly to the camera so that i may use the intervalometer app without purchasing the third-party hardware the app wants me to use. Is there any risk of hurting my camera because the electrical output of the iPhone is different from that of the Cactus V5?