Create you own interval timer on your smart phone with Seconds Interval Timer available for iOS and Android.
Seconds Interval Timer - iOS: https://itunes.apple.com/us/app/seconds-interval-timer/id475816966?mt=8&pt=87596&at=11laMP&ct=ytit
Seconds Interval Timer - Android: https://play.google.com/store/apps/details?id=com.runloop.seconds.free
30 Seconds Interval Timer
30 intervals
15 minutes duration
